Step 1

In a microwave-safe bowl, microwave the butter and chocolate at 30-second intervals, stirring well until smooth. Set aside.

Step 2

In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt.

Step 3

In a large bowl, use a hand mixer to beat the sugar, eggs, and vanilla extract until frothy.

Step 4

Add the chocolate mixture and mix until smooth.

Step 5

Gradually add the dry ingredients and mix until just combined. Wrap the dough in plastic wrap and place it in the refrigerator for at least 1 hour.

Step 6

Preheat oven to 350°F. Line a baking sheet with parchment paper.

Step 7

Roll the dough into balls. Place on the baking sheet at least 2 inches apart. Flatten the balls slightly. Bake the cookies for about 10 minutes.

Step 8

While cookies are baking, cut the marshmallows in half. Once cookies are baked, place a marshmallow (cut side down) into the center of each cookie and lightly press down. Place cookies back into the oven for another 2-3 minutes.

Step 9

Transfer cookies to a wire rack to cool completely.

Step 10

For the chocolate icing, combine all icing ingredients except for the sprinkles in a bowl and mix together with a whisk.

Step 11

Place the wire rack with cookies over a baking sheet. Spoon a small amount of icing onto the top of each marshmallow. Top with sprinkles.