Cream butter and both sugars until light and fluffy, about 3 minutes. Add eggs and vanilla.
Add flour, baking powder, baking soda, and salt. Add pretzel pieces, peanut butter chips, and marshmallow bits.
Drop batter onto a parchment lined baking sheet, about 2 inches apart.
Bake in a preheated 350 degree oven for 12 to 15 minutes, or until the edges are brown. Cool completely on a wire rack.