Preheat oven to 350° and line two large baking sheets with parchment paper. Slice cookie dough into 1/4” rounds. Spread cookies about 1” apart on baking sheet and bake according to package instructions. Let cool completely.
Pour each color sanding sugar into a separate shallow bowl. Using scissors, cut marshmallows in half diagonally and divide halved marshmallows between bags. Dip the cut marshmallow ends in sugar.
Dye the frosting green with a couple drops of food coloring. Place a small amount of frosting on the center of each cookie and place an M&M in the center. Arrange marshmallows around the M&M to look like flower petals.
Preheat oven to 350º F and grease a 10” oven-safe skillet with cooking spray. In a medium bowl, whisk together flour, baking soda, and salt.
In a large bowl using a hand mixer, cream butter and sugars. Add eggs, peanut butter, and vanilla and beat until smooth. Add dry ingredients and beat until completely combined, then fold in REESE’S Peanut Butter Chips. Transfer dough to prepared skillet.
In a medium bowl, combine marshmallow creme and water and microwave on high for 10 seconds. Pour marshmallow creme mixture in a spiral on cookie dough and use a butter knife to swirl into dough.
Bake until cookie is golden and a toothpick inserted in the center comes out clean, 40 minutes. Let cool 10 minutes, then serve.