Preheat the oven to 400°F.

Line a baking sheet with parchment paper.

Gently pat salmon fillets dry with paper towels. Place on the baking sheet, skin side down.

Use a butter knife or spoon to gently spread an equal amount of the softened butter over the top of each salmon fillet.

Sprinkle the tops of the salmon with the salt and black pepper.

Slice the lemon into 1/4-inch thick rounds. Arrange 2-3 lemon slices over the top of each salmon fillet.

Bake the salmon on middle rack of oven until it flakes easily with a fork, 12-15 minutes.

Check to see that salmon is done. Remove from oven or add time as needed.

Squeeze fresh lemon juice over salmon if desired. Serve immediately. Refrigerate leftovers in an airtight container for up to two days.