Peppermint Marshmallow Chocolate Sandwiches

Heat oven to 325 degrees and place rack in center. Line one baking sheet with parchment paper, In a medium bow,. whisk together flour, cocoa, baking soda and salt; set aside.In a medium saucepan, melt together chocolate and butter over medium heat, stirring occasionally. Let stand until cool, about 20 minutes. Stir in sugar and extract until combined. Stir in eggs until combined well. Add flour mixture and stir until a soft dough forms. Roll cookies into 3/4 inch balls. Dip tops in nonpareils and place coated side up, 1 inch apart on prepared sheet. Bake until set but not firm to touch. 10 to 13 minutes. Using a metal spatula, transfer cookies to a wire rack and let cool completely. Meanwhile, prepare Peppermint Marshmallow. Transfer half of Peppermint mixture to a large decorating bag fitted with a 1/2 inch plain tip or coupler. Pipe mounds of marshmallow about 1/2 inch high, on flat side of half of the cookie. Top with remaining cookies, making sandwiches. Store in an airtight container at room temperature in single layers separated by waxed paper up to 3 days.