Spicy Chocolate Sandwich Cookies

Whisk together flour, cocoa powder, salt, pepper, espresso powder, and cinnamon in a large bowl; set aside.

Put butter and granulated sugar in the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until pale and fluffy, about 3 minutes. Mix in egg, milk, and vanilla. Reduce speed to low. Add flour mixture; mix until just combined. Divide dough in half and wrap each piece with plastic wrap; refrigerate at least 1 hour and up to overnight.

Preheat oven to 350 degrees. Roll out dough 1/4 inch thick on a lightly floured surface. Brush any excess flour off dough with a dry pastry brush. Cut dough using a 2 1/2-inch heart-shaped cookie cutter. Transfer heart shapes to baking sheets lined with parchment paper or a nonstick baking mat, spacing 1 inch apart.

Bake cookies until there is a slight resistance when you lightly touch the centers, about 10 minutes. Transfer cookies to wire racks to cool completely.

Fill a pastry bag fitted with a 1/2-inch plain tip with the chocolate whipped cream. Pipe cream onto half of the cookies; top with remaining cookies.