Preheat the oven to 350°F (180°C) and line a baking sheet with parchment paper or a silicone mat.
Cream together the butter and granulated sugar until light in color and fluffy in texture. This will take about 2 minutes.
1 1/2 cups salted butter, softened, 1 1/2 cups granulated sugar
Scrape the sides of the bowl, add in the eggs and cake batter flavoring. Mix until incorporated.
3 eggs, 1 1/2 tsp cake batter flavoring
Next, add flour and baking powder and mix until a soft dough forms.
4 1/2 cups all-purpose flour, 3 tsp baking powder
Add the crushed Oreos and mix just long enough to spread throughout the dough.
20 cookies and cream cookies, crushed
Take small dollops (heaping Tbsp) of marshmallow fluff (half of a 7 oz. container) and drop in the mixer one at a time and gently mix after adding each dollop. Do not overmix, you want ribbons of marshmallow in the dough.
3.5 oz marshmallow fluff (half of a 7 oz container)
Scoop out your dough using a #12 scoop and flatten slightly into a thick puck shape (about 3/4” thick).
Arrange 6 cookies on your prepared baking sheet and bake at 350° F for 12-15 minutes, or until the cookies no longer look wet and glossy.
Allow the cookies to cool slightly on the cookie sheet, then transfer to a cooling rack to finish cooling to room temp.
While your cookies are cooling, make the buttercream by creaming the butter until smooth.
3/4 salted butter, softened
Add the powdered sugar and 2 Tbsp of heavy cream and mix, adding more heavy cream if needed to get the frosting to a pipeable consistency.
4 1/4 cups powdered sugar, 2-4 Tbsp heavy cream
Remove approximately 1/4 of the frosting and place it in a mixing bowl. Add in the marshmallow fluff (other half of the 7 oz container) and mix by hand until smooth. Set aside.
3.5 oz marshmallow fluff (other half of your 7 oz container)
With the remaining 3/4 of frosting still in your mixer, add cake batter flavoring and blue gel food coloring until desired color is reached (you need very little gel!).
3/4 tsp cake batter flavoring, Blue gel food coloring
Whip for 2-3 minutes until nice and fluffy.
Place a piping bag with a large round tip in a tall glass for easy filling.Take the white marshmallow frosting and spoon it into one half of the piping bag (we want the two colors side by side, not on top of one another). If you scrape your spoon on the inside of the cup it helps keep it to one side. Repeat with the blue frosting on the other side of the bag.
Pipe frosting in a swirling motion on top of each cookie.
Add crushed cookies and cream cookies on top and serve.
10 cookies and cream cookies, crushed for garnish
Store in an airtight container on the counter for up to 3 days. Enjoy!