Preheat oven to 350° F
Boil water and cook noodles according to package
Heat up pan at medium heat
Add olive oil and minced garlic and let sizzle for about a minute
Add the onions. Make sure to keep a small amount of water or liquid in the pan so they do not brown- only soften. This will take 10-15 minutes or until soft. Make sure water is also evaporated, if it was added.
Add roasted red pepper and heavy cream
Mix with a hand-held immersion blender (or regular blender, if needed)
When noodles are done, drain and add to 9x13 rectangular casserole dish
Add sauce to casserole dish and mix together
Add in slowly the parmesan cheese and mix until blended with the pasta
Add pinch of red pepper flakes
Bake in oven for 20 minutes
Add mozzarella cheese to top - do not mix
Bake for another 5 minutes
Optional: Garnish with Basil
Serve Immediately