I preheat the oven to 350°F (175°C) and line an 8-inch cake pan with parchment, greasing the sides. In a large bowl, I whisk ¾ cup + 2 tbsp flour, ½ cup sugar, and 1 ¼ tsp baking powder. I add 6 tbsp softened butter, 2 egg whites, 1 ½ tsp vanilla, ¼ cup sour cream, and ¼ cup milk, mixing on medium speed until smooth, about 1 minute. I spread the batter evenly in the pan and bake for 18–20 minutes until a toothpick shows a few crumbs. I cool in the pan for 3–4 minutes, then transfer to a rack. I level the cake top and poke holes across it with a fork. I mix 3 tbsp hot water with 3 tbsp orange JELLO powder and spoon over the cake, letting it soak in.

In a large bowl, I beat 12 oz softened cream cheese and ¾ cup sugar until smooth, about 2 minutes. I add ¼ cup milk and mix until combined. I gently fold in 12 oz Cool Whip until fully incorporated. I divide the mixture evenly into two bowls. For the orange layer, I dissolve the remaining JELLO powder in 2 tbsp hot water and fold it into one bowl. For the vanilla layer, I add 2 tsp vanilla extract to the other bowl.

I line an 8-inch springform pan with parchment around the edges. I place the cooled, JELLO-soaked cake layer in the bottom. I spread the vanilla ice cream mixture evenly over the cake, smoothing with a spatula. I top with the orange ice cream mixture, smoothing again. I cover and freeze for 6–8 hours until solid.

Once frozen, I remove the cake from the springform pan and peel off the parchment. I frost the top and sides with 8 oz Cool Whip, tinting with orange gel color if desired. I pipe extra Cool Whip swirls and garnish with orange candy slices. I freeze again until ready to serve, letting it soften for 10–15 minutes before slicing with a warm knife.