Bring a large pot of salted water to a boil and cook the fettuccine according to package directions until al dente; drain, rinse briefly with cold water to stop cooking, and set aside.
Meanwhile, pour the jarred roasted bell peppers and their liquid into a food processor or blender and puree until smooth.
Heat a large nonstick skillet over medium-high heat and add the butter; when melted, add the shrimp, paprika, and red pepper flakes and cook 3–4 minutes, stirring, until shrimp are pink and opaque.
Add the chopped garlic and sea salt to the shrimp and cook 1 more minute, then remove the shrimp from the pan and set aside; reduce the heat to low.
In the same pan, add the pureed roasted peppers and simmer over low heat for about 10 minutes, stirring often.
Stir in the Half & Half and grated Parmesan and cook 1 minute more, then turn off the heat.
Return the cooked shrimp to the pan, add the drained fettuccine, and toss gently until pasta is evenly coated with the sauce.
Garnish with chopped parsley and additional grated Parmesan if desired, then serve immediately.
