Awesome Chocolate Marshmallow Cupcakes

Ingredients:
16 Tbsp (2 sticks) unsalted butter, room temp plus more for muffin tins
3/4 c unsweetened cocoa powder, plus more for muffin tins
2 c a.p flour
1/2 tsp baking soda
2 tsp baking powder
1/2 tsp salt
2 c sugar
3 large eggs, room temp
1 c sour cream, room temp

For the filling:
1 1/2 c marshmallow creme (7.5 oz jar)
8 Tbsp (1 stick) unsalted butter, room temp

1. Preheat oven to 350°F. Butter two 6-cup jumbo muffin tins: dust with cocoa powder to coat, tapping out excess.In a medium bowl, whisk together cocoa, flour, baking powder, soda, and salt.
2. Cream butter and sugar until light. Add eggs one at a time, beating well after each addition. On low speed, add half the flour mixture, followed by sour cream, ending with remaining flour mixture; mix just until incorporated (do not overmix).
3. Divide batter among prepared muffin cups. Bake until a toothpick inserted in center of cupcake comes out clean, 25-30 mins, rotating tins halfway through baking. Cool in tins, 5 minutes; remove cupcakes and cool, right side up, on a wire rack.
4. Meanwhile, prepare filling: in a medium bowl, whisk marshmallow creme and butter until smooth. Chill until slightly firm, 15 to 30 minutes. Transfer mixture to a piping bag (or a heavy-duty resealable plastic bag, seal, and cut off one corner of the bag to make a 1/8-inch opening).
Using a small melon baller, scoop out center of each cupcake from the bottom, and reserve (you will use this to plug cupcake after filling). Hallow out each cupcake a bit more, discarding crumbs. Fill cavity with filling; replace plgs. Using remaining filling in bag to decorate top of cupcakes.