Chocolate-Mint Sandwich Cookies

Ingredients

• 0.5 teaspoon baking soda 
• 0.5 cup confectioners' sugar 
• 1 large eggs 
• 1 cup flour all-purpose
• 1.5 cups marshmallow fluff 
• 0.3 teaspoon peppermint extract 
• 35 servings food coloring green red
• 0.5 teaspoon salt 
• 1 pinch salt 
• 1 cup sugar 
• 10 tablespoon butter unsalted at room temperature ()
• 6 tablespoons cocoa unsweetened
• 1 teaspoon vanilla extract 

Equipment

• bowl
• baking sheet
• oven
• wire rack
• hand mixer

Directions

1. Mix flour, cocoa, baking soda and salt in a bowl. Using an electric mixer on medium speed, beat butter and sugar until light, about 3 minutes. Beat in egg and vanilla until smooth. Stir in flour mixture until just combined.
2. Divide dough in half. Shape each portion into a log about 9 inches long and 1 1/2 inches in diameter. Wrap in plastic; chill for at least 2 hours and up to 1 day (or freeze for up to 1 month).
3. Preheat oven to 350F.
4. Place racks in upper and lower thirds of oven. Line 2 baking sheets with parchment. Slice dough into 1/4-inch-thick rounds (36 slices per log); place on baking sheets 2 inches apart.
5. Bake until cookies are dry on top, about 10 minutes.
6. Remove to a wire rack; cool. Repeat with remaining dough.
7. Make filling: Using an electric mixer on medium speed, beat butter, confectioners' sugar and salt until combined. Stir in Fluff and peppermint extract. Beat on high until light, about 3 minutes. Divide filling between 2 bowls, add red or green food coloring to each bowl; stir until evenly dyed. Sandwich 2 cookies with a teaspoon of filling. Repeat with remaining cookies and filling.