Bring a large pot of salted water to a rolling boil over high heat. Add the fettuccine pasta and cook according to package directions, about 8-10 minutes, until al dente. Drain and set aside.

In a large skillet, melt 4 tablespoons of butter over medium heat. Whisk in 1/4 cup of all-purpose flour to form a roux.

Gradually add 2 cups of whole milk while whisking to avoid lumps. Cook for about 4-5 minutes until thick and smooth.

Reduce heat to low and stir in 4 ounces of cream cheese and 1 cup of Parmesan cheese until melted and combined.

Gently fold in 1 cup of lump crabmeat and cook for 2-3 minutes to heat through.

Add the drained fettuccine to the skillet, tossing gently to coat in the sauce. Add a splash of reserved pasta water if the sauce is too thick.

Serve immediately, garnished with chopped fresh parsley.