Start by preheating your oven to 400°F (200°C) or prepare your skillet for cooking the salmon.

In a mixing bowl, combine the softened cream cheese, shredded mozzarella, grated parmesan, thawed spinach, garlic powder, and red pepper flakes. Stir until well blended and creamy.

Take each salmon fillet and gently spread the spinach mixture evenly over the top.

In a skillet, heat 2 tablespoons of olive oil over medium heat. Season the salmon fillets with kosher salt and freshly ground black pepper.

Place the salmon fillets skin-side down in the skillet. Cook for about 5-7 minutes until the skin is crispy and golden brown.

Carefully flip the fillets using a spatula and add butter to the skillet. Spoon the melted butter over the salmon as it cooks, about another 5 minutes.

Squeeze fresh lemon juice over the salmon just before removing it from heat.