Brown Butter Chocolate Chip Cookie Bars

• 3/4 cup (170g) unsalted butter (*see notes) 
• 1 tbsp milk powder (optional, **see notes) 
• 3/4 cup (155g) light brown sugar, packed
• 1/3 (65g) granulated or cane sugar
• 1 large whole egg room temperature
• 1 egg yolk room temperature
• 1 TBSP pure vanilla extract
• 1/2 tsp espresso powder (optional) 
• 1 2/3 cups (200g) all-purpose flour leveled and spooned
• 1 TBSP cornstarch
• 3/4 tsp salt
• 1/4 tsp baking powder
• 1/2 tsp baking soda‍
• 1 cup (170g) semi-sweet chocolate chips or baking chocolate bar chopped
• Top with flaky sea salt (optional) 

1. Brown butter in a saucepan over medium heat until golden and nutty.*
2. Remove from heat, pour in a large mixing bowl and stir in milk powder. Let the butter cool for 10-15 minutes.**
3. Preheat oven to 350°F (175°C). Line an 8×8-inch pan with parchment, leaving overhang.
4. When the butter has cooled, whisk in sugars till fully combined and glossy. It will look a little grainy.
5. Add in the egg, egg yolk and vanilla extract. Whisk till combined and smooth.  
6. Add flour, cornstarch, salt, baking powder, and baking soda. Fold gently just until combined.
7. Stir in chocolate.
8. Press dough evenly into prepared pan using lightly damp fingers or an offset spatula.
9. Bake for 15-20 minutes, checking early. Edges should be set and golden; center should look slightly underbaked.
10. Cool  in the pan for 10 mins and transfer to a cooling rack to completely

NOTES: 

*How to Brown Butter (The Right Way)

1. Place the butter in a light-colored saucepan over medium heat.
2. Let it melt completely, then continue cooking. It will foam, then quiet.
3. Swirl the pan occasionally. Watch for golden bits forming on the bottom.
4. When it smells nutty and looks amber, remove from heat.
5. Immediately stir in the espresso powder and milk powder.

You want golden, not burnt. Think toasted hazelnut, not coffee ash.

**Milk Powder
Milk powder deepens the brown butter flavor, giving it that bakery-style, toasted richness. It’s usually found in the baking aisle near evaporated milk or in the international foods section.

• If you can’t find it, you can skip it. Just add 1 TBSP room temp milk to the wet batter.
• The cookies will still be delicious.
• You’ll simply lose a little of that layered, nutty depth.

Think of it as a flavor amplifier, not a requirement.

Storage:

Store cookie bars in an airtight container at room temperature for up to 3 days. The flavor actually deepens after the first day as the brown butter settles.

For longer storage, refrigerate for up to 5 days. Let bars come to room temperature before serving for the best texture.

To freeze, wrap individual bars or the whole slab tightly in plastic wrap, then foil. Freeze for up to 2–3 months. Thaw at room temperature or warm briefly for a just-baked feel.

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