Preheat oven to 350°. Line 3 cookie sheets with parchment paper.
Cream butter, peanut butter, and sugars until well combined. Mix in egg and vanilla. Add salt and baking soda and mix well. Add flour and mix until just combined. Stir in M&Ms.
Scoop large spoonfuls (I used an ice cream scoop) onto prepared cookie sheet and flatten slightly with the tines of a fork. (I got 13.) Press 1 craft stick into each cookie, inserting from one side into the center. Sprinkle with sprinkles.
Bake 8-10 minutes, until edges are brown. Let cool completely before removing from cookie sheet.