Mix butter, peanut butter and sugars together in a medium bowl with a fork until smooth.

Stir in egg until fully incorporated.

Mix in flour, baking soda, baking powder and salt just until combined.

Fold in 1/2 cup of peanut butter chips.

Cover dough and refrigerate for one hour.

Preheat oven to 375 degrees.

Line a cookie sheet or jelly roll pan with parchment paper and use your fingers to pat out the cookie dough to about 1/4 inch thick in a rectangular shape. Leave at least an inch of space around the edges of the sheet for the cookie to expand. (If using a smaller cookie sheet, you may need to use two sheets.)

Sprinkle remaining half cup of peanut butter chips over the top. Press down lightly.

Bake 7-9 minutes or just until edges are golden brown. Center will look under-baked but will continue cooking after the cookie sheet has been removed from the oven.

Let cool before removing to cutting board.

Cut into bars or triangles and serve.

Store in airtight container for up to one week.