01 -
Melt butter and chocolate in microwave, stirring until smooth, then cool 15 minutes.
02 -
Whisk together flour, cocoa powder, baking powder, and salt.
03 -
Beat sugar, eggs, and vanilla until smooth, then blend in cooled chocolate.
04 -
Mix in flour mixture in two batches until just combined.
05 -
Chill dough at least 1 hour until firm.
06 -
Preheat oven to 325°F and line baking sheets with parchment.
07 -
Scoop tablespoon-sized balls onto sheets 2 inches apart.
08 -
Bake 10-12 minutes until crackled on top.
09 -
Add marshmallow halves and return to oven 3 minutes.
10 -
Cool briefly then transfer to wire rack.
11 -
Make icing by whisking all ingredients together.
12 -
Spoon icing over marshmallows and add sprinkles before setting.