Step 1

Preheat the oven to 350°.

Step 2

In the bowl of a stand mixer cream together the butter and sugar until light and fluffy.

Step 3

Scrape the sides of the bowl and add the eggs, root beer flavoring and oil.

Step 4

Mix until combined.Lastly, add in the flour and baking powder. Mix until the dough forms. The dough will be soft.

Step 5

Scoop your dough out into generous 1/3 cup portions. Roll the cookie dough into a ball and then flatten the cookie dough slightly. Repeat with the remaining dough, arrange on pan.

Step 6

Bake at 350° for 11-14 minutes. The cookies will spread slightly and the centers will puff up when they are ready to be taken out of the oven. Allow the cookies to cool on the pan.

Step 7

Make the frosting, by whipping the butter until smooth.

Step 8

Add the powdered sugar, one cup at a time, adding a little bit of milk after each cup of powdered sugar to keep the consistency like a thick frosting.

Step 9

Add the marshmallow creme to the frosting and mix until well combined.

Step 10

Divide the frosting among the cookies and spread to cover the top of the cookie.

Step 11

Serve chilled.