Prepare the Brownie Base: Mix the gluten-free flour, cocoa powder, granulated sugar, eggs, and melted unsalted butter in a bowl until combined. Bake at 350°F (175°C) for 20 minutes until set and let cool completely.

Layer the Ice Cream: Once the brownies have cooled down, spread the coffee ice cream evenly over the brownie base. Place it into the freezer for about 2 hours, or until firm.

Add Vanilla Layer: Carefully add the vanilla ice cream on top, swirling in some chocolate fudge sauce if desired. Spread it evenly, then return the cake to the freezer and let it freeze for at least 4 hours for the best results.

Serve: When ready to serve, slice while the cake is slightly frozen. Allow it to rest for a few minutes to enhance the creaminess, making every bite heavenly.