In a medium size skillet, melt the butter over medium heat. Add the garlic and cook until aromatic, (about 2 minutes), stirring constantly, and taking care not to let the garlic burn.
Sprinkle in the flour and whisk for about 1 to 2 minutes, just to get the flour a little heat and mix with the butter and garlic. Slowly whisk in the milk and cream cheese, whisking until the mixture is smooth. It will look curdled at first, but continue whisking for 2-3 minutes, it will come together to form a smooth, creamy sauce. Stir in the Parmesan cheese, salt, pepper and parsley. Stir until the cheese is melted and the sauce is the desired consistency. (Cook for 2-3 minutes for a thicker sauce or remove right after the cheese is melted for a thinner sauce). Set aside and keep warm.
In a large size Dutch oven or large size sauce pan, over high heat, bring 6 to 8 cups of water to a boil, add a dash of salt and about a tablespoon of oil to the water. Once the water is a consistent rolling boil, add your pasta and reduce heat to medium. Boil pasta until al dente, (about 8 to 12 minutes), stirring occasionally to keep the pasta from sticking together.
In a medium size skillet, add 2 tablespoons butter over medium-high heat, add shrimp and scallops and salt, sauté until shrimp turn an orange color, now, quickly and gently fold in the broccoli and crabmeat.
Add the Alfredo sauce to the Al dente pasta, toss well to coat the pasta in sauce and then gently fold in the seafood mixture. Serve hot.