Heat olive oil in a skillet over medium heat.
Add minced garlic and sauté for 1 minute.
Add sliced bell peppers and cook until slightly softened, about 5 minutes.
Stir in diced tomatoes, Italian seasoning, and a pinch of red pepper flakes.
Simmer for 10 minutes to let the flavors meld together.
Meanwhile, cook spaghetti according to package instructions until al dente.
Drain the spaghetti and add it to the skillet with the sauce.
Toss until the spaghetti is well coated in the sauce.
Serve hot, garnished with chopped fresh basil and grated Parmesan cheese.