Chewy Chocolate Chip Blondies with Oatmeal Cookie Streusel

Name: Chewy Chocolate Chip Blondies with Oatmeal Cookie Streusel
Cook time: 35 min
Total time: 1 min
Ingredients: 12 tablespoons unsalted butter (browned); 1 cup brown sugar (loosely packed); 2 teaspoons vanilla extract; 2 large eggs (lightly beaten); 1 3/4 cups all-purpose flour; 1/2 teaspoon baking powder; 1/2 teaspoon baking soda; 1/4 teaspoon salt; 1 cup chocolate chips; 2/3 cups rolled oats; 2/3 cup brown sugar (loosely packed); 2/3 cup all-purpose flour; 1/4 teaspoon ground cinnamon; 5 tablespoons unsalted butter (softened)

These blondies are chewy and fudgy at the center with caramel notes from browned butter, studded with chocolate chips and finished with a crunchy oatmeal cookie streusel for contrast.

They come together in about 1 hour from start to finish and bake in a single 9×9-inch pan—perfect for dessert, potlucks, or slicing into portable snack bars once the pan has cooled completely.

Why You’ll Love This Recipe

A few small techniques—browning the butter and watching the center for a slight jiggle—create a fudgy, chewy blondie while the oat streusel gives the top a crisp, cookie-like crunch.

Browned butter adds deep, nutty caramel flavor that elevates the entire bar.
Slightly underbaking and using mostly brown sugar yields a dense, chewy center rather than a cakey texture.
The oat-and-cinnamon streusel provides a crunchy, old-fashioned cookie contrast to the gooey interior.
Baked in a single 9×9-inch pan for easy prep, baking, and shareability.

Follow the recipe card above for exact measurements and use the method and tips below to get reliably chewy blondies and a crisp streusel top every time.

Ingredients You’ll Need

12 tablespoons unsalted butter, browned: Browned butter provides the recipe’s caramelized, toffee-like flavor and contributes to a tender, slightly fudgy crumb.
1 cup brown sugar, loosely packed: Brown sugar (blondie batter) keeps the bars moist and chewy while adding a rich molasses note.
2 teaspoons vanilla extract: Vanilla extract rounds and amplifies the browned-butter and chocolate flavors in the batter.
2 large eggs, lightly beaten: Eggs bind the batter and add structure while contributing to the blondies’ dense, fudgy texture.
1 3/4 cups all-purpose flour: All-purpose flour supplies structure; this quantity balances tenderness and chew without making the bars cakey.
1/2 teaspoon baking powder: Baking powder gives a touch of lift so the bars aren’t overly compact; it’s a minor lift compared with cake recipes.
1/2 teaspoon baking soda: Baking soda reacts with the brown sugar to help browning and create a slight chewiness in the crumb.
1/4 teaspoon salt: Salt enhances the sweet flavors and brightens the browned-butter notes—use a pinch to balance the bars.
1 cup chocolate chips: Chocolate chips add pockets of melty chocolate for richness and texture throughout the blondies.
2/3 cups rolled oats: Rolled oats form the base of the streusel, giving it a toothsome, cookie-like crunch.
2/3 cup brown sugar, loosely packed: Brown sugar in the streusel helps the topping caramelize slightly and pairs with the oats for a classic cookie flavor.
2/3 cup all-purpose flour: Flour in the streusel helps bind the oats and sugar so the topping crumbles into distinct pieces instead of dissolving.
1/4 teaspoon ground cinnamon: Ground cinnamon adds warm spice to the streusel and complements the brown butter and oats.
5 tablespoons unsalted butter, softened: Unsalted butter for the streusel provides richness; soft butter works for a crumbly streusel, and you can melt it if you prefer a more cohesive crumble when sprinkling.

How to Make the Blondies

Preheat the oven to 350 degrees F and spray a 9×9-inch baking pan liberally with nonstick spray; set the pan aside while you make the batter.
In a large bowl, whisk the browned butter with the brown sugar until combined. Stir in the vanilla, then add the lightly beaten eggs and whisk until the batter is smooth and glossy.
Add the all-purpose flour, baking powder, baking soda, and salt to the wet mixture. Stir just until the dry ingredients are fully incorporated; do not overmix. Fold in the chocolate chips so they’re distributed through the batter.
Spread the batter evenly into the prepared 9×9-inch pan using a spatula or the back of a spoon so the top is level.
Make the streusel by whisking the rolled oats, brown sugar, flour, and ground cinnamon. Stir in the melted or softened butter until the mixture is moistened and holds together when pinched, then crumble it evenly over the blondie batter.
Bake the bars for 30 to 35 minutes at 350 degrees F. The edges should be golden and set while the center retains a slight, gentle jiggle—this is the cue for a fudgy-chewy interior. If your oven runs cold, add 2–3 minutes; if it runs hot, check a few minutes early.
Remove the pan from the oven and let it cool completely on a wire rack before cutting. Cooling fully lets the center finish setting and yields cleaner slices.

Chewy Chocolate Chip Blondies with Oatmeal Cookie Streusel close-up view

Brown the Butter

Browning butter builds deep toffee-like flavor that’s central to the blondies. Pay attention to visual and scent cues rather than strict timing.

Stop the browning immediately by pouring the butter into a cool bowl once you see amber color and smell a nutty aroma.

Melt butter over medium heat; it will foam, then the foam will subside as milk solids brown.
Look for tiny brown specks and an amber hue; the aroma will change from buttery to nutty.
As soon as the smell and color are right, remove from heat and transfer to a cool bowl to prevent burning.

Bake for a Chewy Center

The key to chewy, fudgy blondies is slightly underbaking so the middle retains moisture and sets as it cools.

Ovens vary—use the center jiggle test and the timing in the recipe as a guide, not an absolute.

Check at 30 minutes: edges should be golden while the center still wobbles a little.
If the center is fully set with no jiggle, you’ve likely baked to a firmer, more cake-like texture.
If you need a few more minutes, add them in 2–3 minute increments until the desired jiggle remains.

Streusel Texture Tips

The streusel should be a mix of crisp and chunky bits that contrast with the blondie’s chewy interior.

Adjust butter temperature to control crumble cohesion: softened butter yields a looser crumble; melted butter makes the topping stickier and more compact.

For the chunkiest streusel, use softened butter and crumble with your fingers.
If you prefer the streusel to meld into the top, use melted butter and press slightly after sprinkling.
Even coverage ensures every bite has both blondie and crisp oat topping.

Tips & Storage

Brown the butter safely: Watch the butter closely as it foams and then turns an amber color with a nutty aroma; when small brown flecks form, remove the pan from heat and transfer the butter to a cool bowl to stop cooking.

Use the center jiggle test: When the edges are golden, give the pan a gentle shake—if the center wobbles very slightly but isn’t liquid, it will set to a chewy, fudgy texture as it cools.

Cooling and slicing: Allow the blondies to cool completely in the pan before cutting so the interior firms up and you get neat slices; warm-cutting will produce ragged edges.

Make-ahead and freezing: Wrap whole cooled bars tightly in plastic and foil or freeze slices between parchment layers in an airtight container. Thaw at room temperature and warm briefly in a 300°F oven for 5–8 minutes to revive the texture.

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Chewy Chocolate Chip Blondies with Oatmeal Cookie Streusel Pinterest pin

Common Questions

Quick oats will work, but the streusel will be finer and less toothsome. Rolled oats give the topping more distinct texture and visible oat pieces.

Either is acceptable: softened butter yields a crumbly, separate streusel; melted butter produces a slightly more cohesive topping. Use melted if you want the bits to adhere more to the blondie top.

Thaw at room temperature, then warm briefly in a 300°F oven for 5–8 minutes or microwave for 10–15 seconds to bring back a freshly baked texture without over-softening the streusel.

Ready to Bake

Follow the recipe card above for exact measurements, brown the butter carefully, and watch the center for a gentle jiggle to achieve reliably chewy blondies with a crisp oat streusel.

Once cooled, slice, wrap, and store or freeze as needed—these bars hold up well and make a great make-ahead dessert or snack.