Preheat oven to 350°F and prepare two 9-inch round cake pans with parchment paper and cooking spray
Mix all dry ingredients (flour, baking powder, baking soda, salt, sugar) in a large bowl
In a separate bowl, whisk together wet ingredients (butter, eggs, milk, vanilla extract)
Combine dry and wet ingredients until smooth batter forms
Divide batter evenly between prepared pans
Bake for 12-15 minutes until a toothpick comes out with just a few moist crumbs
Cool cake layers completely in pans for 10 minutes, then turn out onto wire racks
Remove ice cream from freezer and let soften for 10-15 minutes until spreadable
Place first cooled cake layer in a 9-inch springform pan or on a freezer-safe plate
Spread softened ice cream evenly across first cake layer in ½-inch thickness
Place second cake layer on top, pressing gently to secure
Place assembled cake in freezer for at least 4 hours (overnight preferred)
Prepare whipped cream frosting by whipping heavy cream with powdered sugar and vanilla extract
Remove frozen cake from freezer 30 minutes before decorating
Frost top and sides with whipped cream frosting using a piping bag
Decorate with jimmies, sprinkles, crushed cookies, or chocolate chips
Return to freezer until serving time
Remove from freezer 5-10 minutes before serving for optimal texture
Cut with a hot knife (run under hot water and wipe dry between cuts)
Serve immediately and enjoy your homemade Carvel ice cream cake