Thick and fudgy brown butter blondies swirled with mixed berry jam and finished with pockets of white chocolate for the perfect balance of rich and bright flavor.
- In a small saucepan over medium heat, melt butter. Continue cooking until golden brown flecks form and it smells nutty. Transfer to a large bowl, mix in milk powder if using and cool for 10–15 minutes.
- Preheat oven to 350°F. Line an 8x8 baking pan with parchment paper.
- Whisk brown sugar and granulated sugar into the warm brown butter. Add egg, egg yolk, and vanilla. Mix until smooth and glossy.
- Fold in flour, cornstarch, and salt until just combined. Do not overmix. Mix in white chocolate till combined.
- Spread batter evenly into prepared pan. Dollop jam across the top and gently swirl using a butter knife, but don't go too far into the batter.
- Bake for 25–30 minutes, until the edges are set and lightly golden. A toothpick inserted at the base, not touching the jam shows moist crumbs and no raw batter. Also, the top of the jam is glossy but not liquidy. Let blondies cool in the pan for at least an hour to further set.
Notes:
- Place the butter in a light-colored saucepan over medium heat.
- Let it melt completely, then continue cooking. It will foam, then quiet.
- Swirl the pan occasionally. Watch for golden bits forming on the bottom.
- When it smells nutty and looks amber, remove from heat.
- Immediately stir milk powder if using.
You want golden, not burnt. Think toasted hazelnut, not coffee ash.
**How to Measure Flour (Correctly)
Measuring flour properly makes a big difference in how baked goods turn out. For best results, use a kitchen scale and measure in grams. This ensures consistency and prevents adding too much flour, which can make the cake dry.
If you don’t have a scale:
- Do not scoop flour directly with the measuring cup.
- Use a spoon to gently fill the measuring cup.
- Level it off with the back of a knife.
- Do not pack the flour down.
