M&M's Peanut Butter Brookies - Priscos

Ingredients

• 3/4 all-purpose flour
• 1/4 cup unsweetened cocoa powder
• 1/2 tsp baking soda
• 1/8 tsp salt
• 1/3 cup unsalted butter, softened
• 1/3 cup packed brown sugar
• 1/4 cup granulated sugar
• 1 egg white (reserve yolk for Step 4)
• ½ tsp vanilla extract
• 1 cup all-purpose flour
• 1 egg yolk
• 1/2 tsp vanilla extract
• 1/2 cup M&M'S Peanut Butter Minis, divided