Instructions:

Brownie Layer:

Preheat your oven to 350°F (175°C). Grease and line an 8-inch springform pan with parchment paper.
In a large bowl, whisk together sugar, melted butter, and cocoa powder until smooth.
Beat in the eggs one at a time, then stir in the vanilla extract.
In a separate bowl, whisk together flour and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the brownie batter into the prepared pan and bake for 20-25 minutes, or until a toothpick inserted in the center comes out with moist crumbs.
Let the brownie layer cool completely before assembling the cake.
Assemble the Cake:

Once the brownie layer is cool, spread half of the softened coffee ice cream over the top.
Then, add a layer of the softened chocolate ice cream. Smooth out the top with a spatula.
Whipped Cream Topping:

In a chilled bowl, whip the heavy whipping cream with powdered sugar and vanilla extract until stiff peaks form.
Spread the whipped cream evenly over the top of the ice cream layer.
Freeze and Garnish:

Cover the cake tightly with plastic wrap or aluminum foil and freeze for at least 4-6 hours, or overnight, until firm.
Before serving, remove the cake from the freezer and let it sit for 10-15 minutes to soften slightly.
Garnish with chocolate shavings or cocoa powder, if desired.
Tips:

For a richer chocolate experience, use dark cocoa powder in the brownie layer.
If you prefer a stronger coffee flavor, you can add a tablespoon of instant coffee or espresso powder to the coffee ice cream while softening it.
To make your own whipped cream, use heavy whipping cream with good fat content (at least 36%) and ensure your bowl and whisk are chilled before whipping.
Feel free to experiment with different ice cream flavors! Mint chocolate chip or mocha chip ice cream would also pair well with the brownies.