Make cake according to package instructions. Bake on a jelly roll sheet with a non stick surface. You can use a silicone mat or parchment paper as well.
Line a loaf pan with parchment paper. I sprayed the sides first with non stick spray so the paper would stay and the cake would slide out more easily.
Soften sherbet in microwave until you can spread easily. Layer it on the bottom of the pan and freeze for about 20 minutes. Meanwhile, mix 1 cup of milk and the pudding together. Add a tub of Cool Whip and blend.
Add mixture to top of sherbet in the loaf pan and refreeze another 20 minutes.
Carefully cut the cake to match the size of the loaf pan and place it on top of the Cool Whip layer. Press gently down.
Refreeze for 3+ hours.
Slowly invert pan and pull gently on the paper to release it. Top with fresh raspberries. Cut and serve immediately and refreeze the remainder.
Recipe by A Day in Motherhood at https://www.adayinmotherhood.com/raspberry-sorbet-cake/