Adjust an oven rack to the middle position and heat the oven to 325 degrees.

Grease and flour a 12-cup muffin tin.

Combine the flour, baking soda, and salt in a bowl.

Whisk the water, cocoa, chocolate chips, and espresso in a large bowl until smooth.

Add the sugar, sour cream, oil, eggs, and vanilla and mix until combined.

Whisk in the flour mixture until incorporated.

Divide the batter evenly among the muffin cups.

Bake until a toothpick inserted into a cupcake comes out with few dry crumbs attached, 18 to 22 minutes.

Let the cupcakes in the tin for 10 minutes, then turn them out onto a wire rack and cool completely.

Combine the water and gelatin in a large bowl and let sit until the gelatin softens, about 5 minutes.

Microwave until the mixture is bubbling around the edges and the gelatin dissolves, about 30 seconds.

Stir in the butter, vanilla, and salt until combined.

Let the mixture cool until just warm to touch, about 5 minutes.

Whisk in the marshmallow creme until smooth.

Refrigerate until set, about 30 minutes.

Transfer 1/3 cup of the marshmallow mixture to a pastry bag fitted with a small plain tip; reserve the remaining mixture for filling the cupcakes.

Microwave the chocolate and butter in a small bowl, stirring occasionally, until smooth, about 30 seconds.

Cool the glaze to room temperature, about 10 minutes.

Cut a cone from the top of each cupcake.

Cut off all but the top 1/4 inch of the cone, leaving a circular disc of cake. Discard -better yet, eat! —the bottom of the cone.

Fill each cupcake with 1 tablespoon filling.

Replace the tops,

Frost each cupcake with 2 teaspoons cooled glaze, and let sit for 10 minutes.

Using a pastry bag, pipe curlicues across the glazed cupcakes.

Serve.