Preheat oven to 350 degrees. In a large bowl, combine the flour, the baking soda, the baking powder, and the salt. Set aside.

In a large bowl, beat the butter, peanut butter, granulated sugar and brown sugar together until fluffy. Add the egg and mix well. Add the milk and the vanilla extract. Add the flour mixture and beat thoroughly. Stir in the peanut brittle. Place coating sugar (1/4 cup) in a small bowl. Using 1 ½” diameter scoop, scoop dough and coat tops in sugar. Place on parchment lined baking sheets, leaving a couple of inches between for expansion. Using your fingers, slightly flatten cookies. Bake for 12 to 15 minutes. Do not overbake. Cookies may appear to be underdone, but they are not.

Cool the cookies on the sheets for 1 minute, then remove to a rack to cool completely.