Poke small holes in the cherry tomatoes using a toothpick.

Boil water in a pot, add cherry tomatoes, and blanch briefly on medium heat. Cool in water, peel the skin, and pat dry with a paper towel. In the same pot, cook macaroni according to package instructions and drain.

In a bowl, mix sugar, salt, and vinegar. Add the cherry tomatoes and marinate in the refrigerator for at least 30 minutes.

Slice the onion thinly.

Place butter in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for 30 seconds. Add flour, mix, then gradually add milk while stirring. Add sliced onion, cover loosely, and microwave at 600W for 2 minutes. Stir well.

Add boiled shrimp to the mixture and stir.

In a heatproof dish, layer cooked macaroni and the shrimp mixture. Top with pizza cheese and bake in a toaster oven until golden brown, about 7 minutes.