01 - Whisk heavy cream, whole milk, sugar, salt, and peppermint extract in a bowl until sugar dissolves. Add red food coloring if desired. Pour mixture into an ice cream maker and churn following manufacturer’s instructions. Fold in crushed peppermint candies during the last two minutes of churning. Transfer to a container and freeze for at least 2 hours until firm.
02 - Set oven to 350°F. Line two baking sheets with parchment paper.
03 - In a bowl, whisk together flour, cocoa powder, baking soda, and salt until evenly mixed.
04 - In a large bowl, beat softened unsalted butter and granulated sugar until light and fluffy. Add egg and vanilla extract, then mix until fully incorporated.
05 - Gradually add dry ingredients into the butter mixture, stirring just until combined to form the cookie dough.
06 - Drop tablespoon-sized balls of dough onto prepared sheets, slightly flatten each. Bake for 10 to 12 minutes until cookies are set. Cool completely on a wire rack.
07 - Soften ice cream slightly. Place a scoop between two cookies and gently press to form a sandwich. Repeat with remaining cookies and ice cream.
08 - Wrap each sandwich in parchment paper and freeze for at least 30 minutes before serving.