Preheat your oven to 400 degrees F. Spray a rimmed baking sheet with oil.
Rinse the cod and feel for any bones to remove. Pat the cod dry with paper towels, cut it into serving portions, and place the cod on your baking pan. Wash your hands well.
Place the butter in a small microwave-safe bowl and cover it with wax paper. Soften the butter in the microwave on the defrost setting for just a few seconds. (Don't melt it.) Smash the butter with the back of a spoon.
Peel and chop the garlic and add it to the bowl of butter. Rinse the parsley and pat it dry. Chop up the leaves and add them to the bowl. Add the paprika and stir all of the ingredients until blended and creamy.
Place one tablespoon of garlic butter on top of each piece of cod. Spread the butter across the entire surface of the fish with the back of a spoon or a knife.
Bake the cod on the center rack of the oven for 15 minutes or just until the fish can be easily flaked with a fork.
Squeeze on lemon juice and serve immediately. Add salt at the table if needed. If desired, serve with bread for dipping in the garlic butter from the pan.
Store any leftovers in a sealed container in the refrigerator for up to 3-4 days.
Notes
If you use unsalted butter, you'll need to add some salt. If using salted butter, you may not need to add any more salt, but you can do so according to your taste.