Toss the shrimp with ¼ teaspoon of salt and ¼ teaspoon of black pepper in a medium bowl.
Melt 2 tablespoons of butter and add the olive oil to a large skillet set over medium-high heat. Cook the shrimp until they turn pink and start to curl. Remove the shrimp and set aside.
Bring a large pot of salted water to a boil. Add the pasta and cook it according to the package directions - until al dente.
Drain the noodles, reserving 1 cup of pasta water for the sauce.
Return the pan to medium heat. Melt the butter and add the minced garlic. Cook the garlic until fragrant, about 1 minute, stirring continuously.
Add the flour and remaining salt and black pepper. Whisk until it turns a light, golden color.
Slowly whisk in the heavy cream. Bring it to a gentle simmer, then reduce heat to low heat. Whisk continuously for 3-4 minutes, then add the parmesan cheese. Mix well.
Remove from heat once the starts to thicken. Only return to heat if the sauce is too thin for your liking. If the sauce is too thick, add the pasta water in ¼ cup increments, whisking well.
Add the cooked pasta to the sauce, gently mixing to coat in the cream sauce. Then add the cooked shrimp and stir again.
Serve with fresh parsley and grated parmesan if desired.