Marinating the shrimp in olive oil, garlic, and Italian seasoning is the first step. Try to let them marinate for at least 30 minutes. It’s ok if you can’t. This step is not crucial.
While shrimp is marinating, make the sauce. Melt the butter and saute the minced onion and garlic. Try to mince them as finely as you can, so the sauce is smooth, and nobody gets a big piece of garlic or onion.
Add the flour and let it cook for a couple of minutes. Even if it clumps up, move it around the pan to cook it, or the sauce will taste of raw flour.
Pour in the heavy cream and milk and use a whisk to combine everything until there are no more clumps in the sauce. Without a whisk, it is hard to make the sauce smooth.
Mix the bacon bits and ⅓ cup Parmesan cheese into the sauce. Adjust the seasoning with salt and pepper. Let the sauce simmer just until it thickens up.
While making the sauce, cook the pasta according to package instructions and save a bit of the cooking water to add to the sauce if you feel it is too thick. Cook pasta al dente, do not let it overcook. Drain and set aside. Add a splash of olive oil to it so it won’t stick.
Time to cook the shrimp. Heat a medium-sized skillet until hot and add the shrimp with the oil they were marinating in. Cook them for just a couple of minutes on each side.
Throw the cooked shrimp with any juices left in the pan into the sauce.
Add the cooked pasta to the sauce and mix to combine.
Make the topping: mix the Parmesan and mozzarella cheeses with the panko breadcrumbs, melted butter, minced garlic, chopped sun-dried tomatoes, and chopped parsley.
Transfer pasta to an oven-safe this, sprinkle topping over it, and broil for about 5 minutes or until the breadcrumbs are slightly brown and the cheeses are melted. Serve immediately.