In a skillet over medium heat, add 2 tablespoons of olive oil and the minced garlic. Saute until fragrant, about 1 minute.
Add chopped spinach to the skillet and cook until wilted, about 2-3 minutes. Remove the skillet from heat and let the spinach cool slightly.
In a mixing bowl, combine the cream cheese, Parmesan, red pepper flakes, and capers.
Add the cooked spinach to the cheese mixture and stir until well combined. Season with salt and pepper to taste. Set aside.
Place the salmon fillets on a cutting board and slice each fillet horizontally along the side to create a pocket for stuffing. Be careful not to cut all the way through.
Drizzle the salmon fillets with the remaining 1 tablespoon of olive oil and season with salt and pepper to taste.
Stuff each salmon fillet evenly with the spinach and cheese mixture. Press gently to close the fillets.
Arrange the stuffed fillets onto a parchment-lined baking sheet and bake for 12-15 minutes, or until the salmon is cooked through and flakes easily with a fork.
Transfer to a serving plate and garnish with parsley. Serve with lemon wedges.