1Preheat oven to 375 degrees F (190 degrees C). Cover the bottom of a baking dish with the olive oil and arrange salmon in the dish.
2Process walnuts and garlic in a food processor until evenly chopped. Add cilantro, butter, salt, and pepper to walnut mixture; process until a paste forms. Spread walnut paste onto the salmon.
3Bake in the preheated oven until the salmon flakes easily with a fork, 20 to 25 minutes.