Preheat the oven to 395°F/200°C. (Instant Pot instructions can be found in the notes below)
To a baking dish or a cast-iron dish, add the cherry tomatoes. Drizzle with extra virgin olive oil, and season with salt and pepper. Give everything a good stir so that the tomatoes are well coated in oil.
Make room for the feta block, and place it in the center of the pan. Drizzle with olive oil, and season with crushed chili flakes, salt, and pepper.
Bake in the oven for 30 minutes or until the cherry tomatoes have softened and burst. Meanwhile, cook the pasta in salted water (no oil!) until al dente. Reserve 1 cup of pasta cooking water.
Remove the dish from the oven. The feta will be really soft. Add crushed garlic and chopped fresh basil leaves.
Using a spoon or a fork, mix the feta with everything else in the pan and lightly mash the cherry tomatoes. Taste the sauce, if it's acidic, mix in the sugar.
Add in the cooked pasta, and mix everything until the pasta is well coated. If needed, loosen the sauce with a splash of pasta cooking water (you might need it if reheating the pasta later).
Garnish with extra chopped fresh basil, and serve warm.