Preheat your oven to 400°F. While it heats, mince the garlic cloves finely and slice the lemon into thin rounds. Pat the salmon fillet dry with paper towels—this helps the seasonings stick better and allows the skin to crisp slightly during baking. Measure out all remaining ingredients so everything is ready to go when you start assembling.

Tear off a large piece of foil and place it in a baking dish or directly on a baking sheet. Brush the foil lightly with olive oil to prevent sticking. Lay the salmon skin-side down on the foil. Drizzle the top of the fillet with the remaining olive oil, then scatter the minced garlic evenly across the surface. Sprinkle the Italian seasoning, salt, and freshly ground black pepper over the salmon. I like to taste a tiny pinch of the seasoning mix before applying it to make sure the salt level feels right—it should taste just slightly salty on its own.

Arrange the lemon slices from Step 1 over the seasoned salmon—they'll release their juice as the fish bakes and infuse it with bright citrus flavor. Dot the top of the fillet with small pieces of the room-temperature butter; this will melt and create a rich, silky sauce. Fold the foil up and over the salmon, sealing the edges tightly to trap steam. This creates a gentle, moist cooking environment that keeps the salmon tender and juicy.

Place the foil packet in the preheated 400°F oven and bake for 10-15 minutes, depending on the exact thickness of your fillet. The salmon is done when it flakes easily with a fork and the flesh is opaque throughout—I check by gently pressing the thickest part; it should feel just slightly firm but not hard. Carefully open the foil packet (watch out for the hot steam!) and transfer the salmon to a serving plate. Pour the accumulated butter and lemon sauce from the foil over the top and serve immediately.