Warm butter in a large saucepan over low heat. Add garlic and cook gently until fragrant, then add cream, parmesan and pepper, increase heat to medium and let simmer until it starts to thicken slightly.
Add wine or lemon juice and simmer 2 more minutes. Reduce heat to low and add pasta, seafood and parsley, tossing gently. Cook gently until heated through, tasting and adding a bit of salt if necessary. If it becomes too thick, add in a little pasta cooking liquid a bit at a time until the desired consistency.
Serve in pre warmed bowls immediately. Fresh parsley, grated parmesan and ground pepper make lovely simple garnishes.