Fudgy Hazelnut Blondies — Easy, Gooey Bars

Melted chocolate, a glossy Nutella ribbon and a crackly top meet in these Easy Fudgy Nutella Blondies. I developed this version after testing it eight times to get a fudgy center without a raw texture. The batter uses melted butter and a single egg to keep chew and shine. A swirl of Nutella gives deep hazelnut flavor without extra steps. This is the version I perfected during weekend recipe testing and at-home bake-offs. Read on for exact weights, timing cues, and failproof techniques so you can bake them with confidence. If you like baking simple sweets after a homemade loaf, serve them warm with a slice of simple homemade bread or a scoop of ice cream for an easy dessert.

Why This Recipe Works

Melted butter and a lower egg ratio create a dense, fudgy crumb rather than a cakey one.
Less flour and more sugar (brown sugar for moisture) keep the interior glossy and chewy.
Swirling Nutella after pouring the batter preserves texture and produces concentrated pockets of hazelnut flavor.
Baking in a square pan at moderate heat (175°C / 350°F) cooks edges fully while the center stays fudgy.
Quick cooling in the pan lets the bars set without overbaking, preventing dryness.

Ingredients Breakdown

All-purpose flour — 240 g (2 cups): Provides structure. Spoon and level for accuracy. Overmeasuring makes bars dry.
Unsalted butter — 170 g (3/4 cup / 6 tablespoons): Melted and slightly cooled. Butter adds richness and helps the blondies be fudgy.
Light brown sugar — 220 g (1 cup, packed): Adds moisture and deeper flavor than white sugar alone.
Granulated sugar — 50 g (1/4 cup): Helps the crackly top form.
Large egg — 1 (about 50 g): Binds and adds lift. Using two eggs will make bars more cake-like.
Vanilla extract — 5 ml (1 teaspoon): Enhances flavor.
Baking powder — 2 g (1/2 teaspoon): Small lift without fluffing the crumb.
Fine salt — 3 g (1/2 teaspoon Diamond Crystal or 1/4 teaspoon Morton’s): Balances sweetness. If using Morton, reduce amount.
Nutella — 200 g (about 3/4 cup + 2 tablespoons): For swirls and pockets of hazelnut-chocolate flavor. Gently warm to make swirling easier.
Optional: chocolate chips — 100 g (1 cup) or chopped toasted hazelnuts 60 g (1/2 cup): Adds textural contrast.

Substitutions with impact warnings:

Brown sugar swap: Using all granulated sugar yields a drier, less tender bar.
Butter swap: Use clarified butter for longer shelf life but expect a slightly less rich flavor.
Nutella swap: Use any chocolate-hazelnut spread, but note that lower-fat spreads reduce gloss and fudginess.
Gluten-free: Replace flour with a 1:1 gluten-free blend and add 1/4 tsp xanthan gum; expect slightly different crumb.

Essential Equipment

23 cm (9 x 9 inch) square baking pan — have this size ready; smaller pans will overflow, larger pans yield thinner bars.
Parchment paper — for easy removal and clean edges.
Digital kitchen scale — for precise dry-ingredient weights.
Rubber spatula and whisk — for folding and smoothing batter.
Small offset spatula or butter knife — for swirling Nutella.
Instant-read thermometer (optional) — to check internal doneness if needed.

If you lack a square pan, use an 18 x 26 cm (7 x 11 inch) pan but reduce bake time by 3–5 minutes and watch closely.

Prep Time: 15 minutes; Cook Time: 22–28 minutes; Inactive Time: 10 minutes cooling; Total Time: 45 minutes; Servings: 12 bars.

Step 1: Preheat and prepare the pan

Preheat the oven to 175°C (350°F). Line a 23 cm (9 x 9 inch) pan with parchment, leaving a 2–3 cm (1 inch) overhang for easy lifting. Lightly butter the parchment so the batter slides.

Step 2: Melt butter and combine sugars

Melt 170 g (3/4 cup / 6 tablespoons) unsalted butter in a small saucepan or microwave. Stir in 220 g (1 cup packed) light brown sugar and 50 g (1/4 cup) granulated sugar until glossy and mostly dissolved, about 30 seconds; let cool 3 minutes.

Step 3: Add egg and vanilla

Whisk in 1 large egg (about 50 g) and 5 ml (1 teaspoon) vanilla quickly until smooth, about 20 seconds. The mixture should look shiny and thick.

Step 4: Fold in dry ingredients

Sift together 240 g (2 cups) all-purpose flour, 2 g (1/2 teaspoon) baking powder, and 3 g (1/2 teaspoon Diamond Crystal / 1/4 tsp Morton) fine salt. Add to the wet mixture and fold with a rubber spatula just until no dry streaks remain; do not overmix — stop as soon as combined (about 10–15 folds).

Step 5: Add mix-ins

Fold in 100 g (1 cup) chocolate chips or 60 g (1/2 cup) toasted chopped hazelnuts if using, 4–6 gentle turns. The batter should be thick and glossy.

Step 6: Pour, dollop, and swirl Nutella

Spread the batter evenly in the prepared pan. Warm 200 g Nutella in a microwave-safe bowl for 10–15 seconds until pourable but not hot. Dot Nutella across the surface with teaspoons. Use an offset spatula or a skewer to make 6–8 gentle S-shaped swirls. Swirl only while the batter is still cold — over-swirl will blend Nutella in and reduce pockets.

Step 7: Bake and check doneness

Bake 22–28 minutes at 175°C (350°F). Edges will be set and lightly browned; center should look just set but fudgy. Insert a toothpick in the center — it should come out with a few moist crumbs, not wet batter. If using an instant-read thermometer, aim for 88–93°C (190–200°F) in the center. Cool the pan on a wire rack for 10 minutes.

Step 8: Chill slightly and cut

Lift blondies from pan using parchment overhang. Cool 20–30 minutes for cleaner slices; for fudgier bars, cool only 10 minutes and cut warm using a sharp knife dipped in hot water and wiped dry between cuts. Resting allows the center to finish setting.

Expert Tips & Pro Techniques

Common mistake: overbaking makes blondies dry. Set your timer for the minimum time and test at 22 minutes. Edges will firm before the center does.
Use a scale for flour. Measuring by cup varies and causes dry results. 240 g (2 cups) is precise.
Warm Nutella slightly to swirl. Too hot will sink; too cool will tear the batter.
Make-ahead: Bake, cool, and wrap in plastic. Store at room temperature for one day or refrigerate up to 4 days. Slice just before serving. For travel, cut into squares and freeze on a tray then bag.
Professional technique for home: use a blowtorch or hot knife for glossy tops when serving — gently warming the Nutella pockets reactivates shine and makes each bite molten.
To get thin, crisp edges, place the pan on a preheated baking sheet for the first 5 minutes of bake time.

Storage & Reheating

Refrigerator: Store cooled bars in an airtight container for up to 4 days. Press a sheet of parchment between layers to prevent sticking.
Freezer: Freeze single bars on a tray until firm, then wrap individually in plastic and place in a freezer bag for up to 3 months. Thaw in the refrigerator overnight, then bring to room temperature before serving.
Reheating: Reheat at 160°C (325°F) for 6–8 minutes to warm through and revive fudginess. Avoid microwaving for more than 10–12 seconds per bar — the texture can become gummy.

Variations & Substitutions

Gluten-Free Version: Use 240 g of a 1:1 gluten-free flour blend (such as Bob’s Red Mill) and add 1/4 tsp xanthan gum. Bake time may increase by 2–4 minutes.
Vegan Swap: Replace butter with 170 g coconut oil and the egg with 1/4 cup (60 g) aquafaba or a flax egg (1 tbsp ground flax + 3 tbsp water). Texture will be slightly crumblier and less glossy.
Extra-chocolate: Fold 100 g chopped dark chocolate into the batter and reduce chips. Keep Nutella swirl the same.
Peanut butter twist: Replace half the Nutella with smooth peanut butter for a nut-duo bar. Swirl proportions remain 200 g total.
Upscale finish: Sprinkle flaky sea salt on top immediately after baking for a sweet-salty contrast.

Serving Suggestions & Pairings

Serve warm with a scoop of vanilla bean ice cream and a drizzle of extra Nutella for a decadent dessert.
Pair with a strong espresso or mocha to balance sweetness; for a lighter option, try green tea.
Offer these blondies after a casual dinner of air-fried mains — they follow nicely after air fryer family meal recipes.
For a potluck or picnic, serve with fruit skewers and a citrusy salad to cut sweetness; they go well alongside hearty sides like air-fryer loaded potatoes or twice-baked potatoes at the main course.

Nutrition Information

Serving size: 1 bar (1 of 12). Amount per serving (estimates):

Calories: 340 kcal
Total Fat: 19 g
Saturated Fat: 9 g
Cholesterol: 45 mg
Sodium: 120 mg
Total Carbohydrates: 43 g
Dietary Fiber: 2 g
Sugars: 28 g
Protein: 4 g

Nutrition values are estimates. Actual values may vary based on specific ingredients and preparation methods.

Frequently Asked Questions

Q: Why did my blondies turn out dry?
A: Most often from overbaking or too much flour. Use a scale, check at 22 minutes, and remove when the center still looks slightly moist.

Q: Can I make this without eggs?
A: Yes. Use 60 g aquafaba or a flax egg (1 tbsp ground flax + 3 tbsp water). Expect a slightly different crumb and less gloss.

Q: Can I double this recipe?
A: Yes — double ingredients and bake in a 33 x 23 cm (13 x 9 inch) pan. Bake time will be similar; check at 25 minutes and add time as needed. Avoid doubling in a single small pan.

Q: Can I prepare this the night before?
A: Absolutely. Bake and cool, then cover tightly. Bring to room temperature before serving or reheat briefly in a 160°C (325°F) oven for 6–8 minutes.

Q: How long does this keep in the fridge?
A: Stored in an airtight container, these keep 3–4 days in the refrigerator. For best texture, bring to room temperature before serving.

Q: Can I use a stand mixer?
A: You can, but mixing by hand preserves the fudgy texture. If you use a mixer, mix on low and stop as soon as dry streaks disappear.

Q: How do I get clean slices?
A: Chill 20–30 minutes or use a hot, dry knife wiped between cuts. Slightly chilled bars cut cleaner.

Conclusion

If you want more inspiration for chocolate-forward treats, check out this take on Broma Bakery’s fudgy Nutella brownies for a different approach to the same flavor pairing. For another tested, crowd-pleasing fudgy bar, see the recipe at Cookies and Cups’ fudgy Nutella brownies for ideas on texture and technique.

Enjoy these blondies warm, and remember: remove them just shy of fully set for perfect fudginess.