Rich Cocoa Cupcakes with chocolate chips and a ganache filling topped with a fluffy marshmallow frosting!
Preheat oven to 350º. Line two 12-cup muffin pans with paper liners.
Sift dry ingredients into a bowl. Set aside. With a mixer, beat sugar and butter till light and fluffy, about 2 minutes. Add eggs, one at a time, beating until well incorporated. Add vanilla and mix.
Add half the dry ingredients, the hot water, then the rest of the dry ingredients, beating just until blended after each addition. Let batter sit for 5 minutes. Stir in chocolate chips, then divide batter into muffin tins.
Bake 22-25 minutes or until a toothpick inserted into the middle of a cupcake comes out with just a few moist crumbs. Cool in tins.
To make filling, place cream in a 4 cup Pyrex measuring cup or microwave safe bowl. Microwave just to boiling. Add chocolate chips. Let stand a minute, then whisk till smooth. Let stand at room temperature until cool and thick, at least 2 hours.
To make icing, whisk 1/3 cup water, sugar, egg whites, cream of tartar and salt in large heatproof bowl. Set over a saucepan of gently simmering water and beat with a mixer until soft peaks form (about 5 minutes). Remove bowl from saucepan and continue mixing till frosting is cool and very fluffy. (about 2 more minutes). Mix in vanilla.
Using your thumb or cupcake corer (I found mine at Target), press down into center of cupcake to form a deep opening. Spoon ganache into each opening.
Frost cupcakes, making generous peaks. May be made a day ahead and stored at room temperature.
Adapted from Bon Appetit.