Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a mixing bowl, combine the sifted flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk together until well mixed.

In another bowl, whisk together the egg, milk, vegetable oil, and vanilla extract until fully combined.

Pour the wet ingredients into the dry ingredients and mix with an electric mixer on medium speed for about 2 minutes until smooth.

Divide the batter evenly between the two prepared cake pans.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely.

Once the cakes are completely cooled, place one layer on a cake stand or serving plate.

Spread one pint of softened vanilla ice cream evenly over the top of the first cake layer. Use a spatula to smooth it out.

Place the second cake layer on top of the ice cream layer, pressing down gently.

Cover the entire cake with plastic wrap and freeze for at least 2 hours, or until the ice cream is firm.

In a chilled mixing bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract.

Using an electric mixer, whip the cream on medium-high speed until stiff peaks form. This will ensure a light and fluffy topping.

Remove the cake from the freezer and spread the whipped cream evenly over the top and sides of the cake.

Decorate with chocolate shavings and sprinkles as desired.

Return the decorated cake to the freezer for an additional 30 minutes to set the whipped cream.

Slice and serve the cake directly from the freezer for the best texture.