Preheat the oven to 400°F (200°C).
Toss halved Brussels sprouts with 1 tablespoon olive oil, salt, and pepper.
Spread Brussels sprouts evenly on a baking sheet and roast for 20-25 minutes until golden and tender.
While roasting, pat cod fillets dry using paper towels.
In a small bowl, combine melted butter, remaining olive oil, garlic, lemon juice, lemon zest, smoked paprika, salt, and pepper.
Brush cod fillets generously with the butter mixture.
Heat a skillet over medium-high heat and sear cod fillets for 2-3 minutes per side until golden and cooked through.
Assemble bowls by placing cooked quinoa or rice as the base, topped with roasted Brussels sprouts, then the cod fillets.
Garnish with chopped fresh parsley and additional lemon zest if desired. Serve warm.