With just one bowl and a whisk, the classic peanut butter and chocolate combo come together in an irresistible bar cookie - the Peanut Butter Blondie.
Preheat oven to 350F. Line a 9x13 inch brownie or cake pan with parchment paper, leaving a bit hanging over the sides.
In a medium bowl, whisk together melted butter and brown sugar. When combined, whisk in peanut butter. Add eggs, egg yolk and vanilla. Whisk together once more.
Switch to a rubber spatula and gently mix in salt, baking powder and flour. When almost combined, add almost all of the mini-chocolate chips (reserve a few tablespoons for sprinkling on top).
Turn out dough into prepared pan and use the spatula to press into all corners of the pan. Sprinkle with remaining chocolate chips.
Bake in preheated oven for 22-32 minutes, until center is set and a toothpick inserted into center comes out with only a few moist crumbs. Edges should be starting to brown. Remove from oven and allow to cool to room temperature before cutting. Store in an airtight container for up to a week.