Grate the Parmesan cheese, finely chop the onion, and mince the garlic cloves. Pat the salmon fillets completely dry with paper towels. Season both sides of the salmon with garlic powder, sweet paprika, and 1/2 teaspoon each of salt and pepper.

Heat olive oil and butter together over medium-high heat in a large nonstick skillet. Once the butter melts and starts to foam, add the salmon fillets. Sear without moving for 3-4 minutes per side until golden-brown. Remove from skillet and set aside.

Reduce heat to medium. Add minced garlic and chopped onion to the same skillet. Cook, stirring frequently, until soft and fragrant, about 2 minutes. Stir in dried thyme and remaining 1/2 teaspoon each of salt and pepper. Add dry orzo and toast for 1 minute, stirring constantly.

Pour in chicken broth and bring to a boil. Reduce heat to medium-low to maintain a gentle simmer. Cook uncovered, stirring occasionally to prevent sticking, until orzo is tender but slightly firm to the bite with most liquid absorbed, about 8 minutes.

Add baby spinach in handfuls, stirring until wilted, about 2 minutes. Stir in lemon juice and freshly grated Parmesan. If orzo seems too thick, add broth 1/4 cup at a time until creamy. Taste and adjust salt.

Nestle seared salmon fillets back into the skillet, gently pressing into the orzo. Simmer together for 2-3 minutes until salmon reaches 145°F internal temperature and is heated through.

Remove from heat and top with freshly ground black pepper and chili flakes if desired. Serve immediately while hot and creamy.