Makes 12 cupcakes

To ensure an appropriately thick filling, be sure to use marshmallow creme (such as Fluff or Kraft Jet-Puffed Creme), not marshmallow sauce.

INGREDIENTS:
CUPCAKES
1 cup all-purpose flour
1/2 teaspoon baking soda
1/4 teaspoon Salt
1/2 cup boiling water
1/3 cup cocoa powder
1/3 cup semisweet chocolate chips
1 tablespoon instant espresso
3/4 cup sugar
1/2 cup sour cream
1/2 cup vegetable oil
2 large eggs
1 teaspoon vanilla extract

FILLING:
3 tablespoons water
3/4 teaspoon unflavored gelatin
4 tablespoon (1/2 stick) unsalted butter, softened
Pinch salt
1 teaspoon vanilla extract
1 1/4 cups marshmallow créme

GLAZE
1/2 cup semisweet chocolate chips
3 tablespoons unsalted butter

INSTRUCTIONS
1. MAKE BATTER Adjust oven rack to middle position and heat oven to 325 degrees. Grease and flour 12-cup muffin tin. Combine flour, baking soda, and salt in bowl. Whisk water, cocoa, chocolate chips, and espresso in large bowl until smooth. Add sugar, sour cream, oil, eggs, and vanilla and mix until combined. Whisk in flour mixture until incorporated. Divide batter evenly among muffin cups. Bake until toothpick inserted into cupcake comes out with few dry crumbs attached, 18 to 22 minutes. Cool -cupcakes in tin 10 minutes, then turn out onto wire rack and cool completely.

2. PREPARE FILLING Combine water and gelatin in large bowl and let sit until gelatin softens, about 5 minutes. Microwave until mixture is bubbling around edges and gelatin dissolves, about 30 seconds. Stir in butter, vanilla, and salt until combined. Let mixture cool until just warm to touch, about 5 minutes, then whisk in marshmallow creme until smooth; refrigerate until set, about 30 minutes. Transfer 1/3 cup marshmallow mixture to pastry bag fitted with small plain tip; reserve remaining mixture for filling cupcakes.

3. ASSEMBLE CUPCAKES Microwave chocolate and butter in small bowl, stirring occasionally, until smooth, about 30 seconds. Cool glaze to room temper-ature, about 10 minutes. Cut cone from top of each cupcake and fill cupcakes with 1 tablespoon filling each. Replace tops, frost with 2 teaspoons cooled glaze, and let sit 10 minutes. Using pastry bag, pipe curlicues across glazed cupcakes. Serve. (Cupcakes can be stored in airtight container at room temperature for 2 days.)