Step 1

Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper so that it overhangs on two opposite sides. Grease the lining and any exposed pan.

Step 2

Whisk together the flour, baking powder, and salt. Set aside.

Step 3

Using an electric mixer on medium speed, beat the butter, brown sugar, and sugar until light and fluffy. Mix in the cookie butter.

Step 4

Add the eggs, one at a time, mixing well after each addition. Mix in the vanilla.

Step 5

Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of the milk. Mix just until combined or a few streaks of flour remain.

Step 6

Stir in the chocolate chips.

Step 7

Transfer the batter to the prepared pan, and spread evenly.

Step 8

Bake 35 to 40 minutes, or until the edges and top are browned, and a pick inserted into the center comes out clean.

Step 9

Cool completely in the pan on a wire rack before serving.