Preheat oven to 350 degrees Fahrenheit and lightly grease cookie sheets or line them with nonstick baking mats.
In the bowl of an electric mixer, cream together butter, cream cheese, granulated and brown sugar, egg, peanut butter and vanilla.
In a separate bowl, stir together flour, baking powder, baking soda, and salt. Add it to the wet mixture and mix until incorporated.
Scoop or roll dough into 1 1/2" balls and place on cookie sheets, at least 2" apart. Press dough balls down with the palms of your hand to flatten, then press three Candy Corn M&M's into the top of each cookie.
Bake for approximately 8-9 minutes or just until done. Don't over bake or they won't be soft! Let cool on cookie sheets for a few minutes, then carefully remove them to a cooling rack to cool completely. Store in an airtight container.