Preheat oven to 400 degrees. Remove shells from shrimp if they are still on. Pat dry shrimp on paper towels, if they're at all wet, the sauce will be runny.
Place butter in a large glass baking dish and place in the oven for 5 minutes. Take it out and add salt, garlic, and 1 tbsp of the parsley. Stir it up and then place shrimp on top of this butter mixture in a single layer. Bake this for another 5 minutes, uncovered.
Remove the dish from oven, turn over each shrimp, sprinkle with the lemon juice and the remaining parsley. Return it to the oven and bake it for an additional 8 minutes.