Bring a large pot of salted water to a boil.

In a large, deep skillet, add sunflower oil and garlic cloves over medium heat. Cook until the garlic cloves golden and sizzling, about 2 minutes. Remove garlic cloves from the skillet and add zucchini. Do not discard the oil in the skillet.

Add zucchini to the skillet. Lightly fry zucchini for 8-10 minutes, tossing until they are tender and golden. Remove zucchini from the skillet and set on a plate.

Add spaghetti to the pot. Cook until very al dente, about 6 minutes. While pasta is cooking, heat the skillet over medium heat. Add 2 cups pasta water to the skillet and bring to a simmer.

When pasta is al dente, transfer the spaghetti to the skillet directly with tongs. Add zucchini, butter, and a pinch of salt and pepper. Use tongs to vigorously stir.

Remove from heat. Slowly add Parmesan cheese and basil to the pan. Continue to stir until the cheese is melted and the sauce is silky. Top with additional basil and cheese and serve.