Preheat your oven to 400°F.
Line a baking sheet with parchment paper. Place the salmon fillets on the baking sheet skin-side down. Drizzle olive oil and lemon juice over the fillets, and season with salt, pepper, and dill. Bake in the preheated oven for about 15 minutes, or until the salmon is cooked through and flakes easily with a fork.
Prepare orzo according to package directions.
In a large skillet over medium heat, melt the butter. Add the garlic and sauté for about 1 minute until fragrant, making sure not to brown. Stir in the cooked orzo and red pepper flakes (if using). Mix well to combine. Add the cheese and spinach to the orzo, stirring until the spinach wilts and the cheese melts. Season with salt and pepper to taste.
Once the salmon is done, remove it from the oven. Plate the garlic butter orzo and place a salmon fillet on top of each serving. Garnish with fresh parsley and lemon wedges.