Cook the penne according to the package directions. Drain.
Meanwhile, heat the oil in a large saucepan over medium heat.
Add the bell peppers, ½ teaspoon salt, and ¼ teaspoon black pepper. Cover and cook for 4 minutes.
Stir in the garlic and red pepper flakes and cook for 1 to 2 minutes.
Add the pasta sauce and cook until heated through, about 3 minutes.
Divide the pasta among individual bowls. Top with the sauce, a dollop of the ricotta, and ¼ teaspoon black pepper.