Prepare funfetti cake and bake in 2, 9 or 8 inch round baking pans. Let cool completely on a wire rack.
Line a springform pan or one of the round baking pans with plastic wrap (clean first to remove any crumbs).
Once the cakes are cool, let the ice cream sit on the counter for 15 minutes or until it’s slightly softened and spreadable.
Carefully cut the domes off each cake with a serrated knife so they are evenly flat.
Place one of the cakes on the bottom of the plastic lined pan.
Spread the ice cream all over the bottom cake layer, then add the second cake on top.
Wrap the whole cake with plastic wrap well and then with foil. Place in the freezer to chill for at least 3 hours.
To make the whipped frosting, place a metal or glass mixing bowl and the beaters in the freezer to chill for 15 minutes Add the heavy cream and beat with an electric mixer until soft peaks form, a few minutes. Add the powdered sugar and vanilla extract and continue to beat until stiff peaks form, fold in jimmies sprinkles. The peaks should hold their shape when scooped with a spoon.
Frost the entire cake with an offset spatula or butter knife (sides and top) with the frosting. Add leftover frosting to a piping bag with a jumbo star tip to decorate the edges. Decorate with sprinkles all around the top and the bottom edges. Place back in the freezer to chill for 1-2 hours (or longer if needed).
When ready to serve and cut, let the cake sit out at room temperature for a few minutes to make the slicing easier. Enjoy!