I preheat my oven to 425°F (≈ 218°C). Then I cut a large sheet of foil, enough to fold up around the salmon on all sides but leave the top somewhat open so steam can escape. I place the foil on a baking sheet for stability.
Next, I combine the softened butter, lemon juice, olive oil, minced garlic, grated Parmesan, Italian seasoning, salt, pepper, and chopped parsley in a bowl. I stir it until it forms a thick spreadable mixture—one that stays on top of the salmon.
I lay the salmon fillet skin-side down on the foil, then spread the garlic-herb butter mixture evenly over the top. I fold up the foil sides, leaving some space or loosely tenting so it isn’t tightly sealed. Bake for 10-12 minutes (depending on thickness), then switch to broil for 1-2 minutes to brown the top. When done, the salmon should flake easily and be opaque.