Remove the heads & the shells from the shrimps. To divide, use a small, sharp knife to make a shallow slit along the back side of each shrimp, from the head to tail, in order to expose the vein & remove it.
Place a pan on high heat. Sprinkle some olive oil over the shrimps, season with salt and some freshly ground pepper. When your pan gets hot add the shrimps and saute for 30 seconds on each side. After, transfer to a plate and set aside.
Place the pan back on high heat. Add the chopped onion to the pan. Add 2 tablespoons of olive oil, 1/2 a teaspoon of granulated sugar and a pinch of chili flakes. Add also 1 clove of garlic and 40 ml of Ouzo. While Ouzo evaporates, add your cherry tomatoes.
Time for pasta. Add your stock and the pasta. Start mixing and lower the heat to medium-high. Simmer for 10 minutes while stirring often.
When your sauce has thickened, add 50 gr of butter and mix, the butter will help thicken your sauce further. After that, remove pan from heat.
Add the shrimps, finely chop 5-6 basil leaves and sprinkle over the top, grate the zest of 1 lemon and mix. Add some grated parmesan (optionally) and mix again.