Preheat the oven to 400°F (200°C). Line a rimmed baking sheet with aluminum foil and spray or brush lightly with oil to prevent sticking.
Place the chopped broccoli in the center of the prepared sheet pan. Drizzle with 2 1/2 tablespoons olive oil and add 1 minced garlic clove; toss to coat evenly. Season with salt and pepper.
Spread the broccoli toward the edges of the pan, leaving space in the center for the salmon fillets.
Season the bottoms of the salmon fillets with salt and pepper and arrange them in the center of the baking sheet, about 3/4 inch apart.
In a small bowl whisk together 1 1/2 tablespoons mayonnaise, 1 1/2 teaspoons lemon juice, 1 minced garlic clove, and a pinch of salt and pepper. Brush about 1/2 tablespoon of the mixture over the top of each fillet.
In another bowl combine 1/4 cup grated Parmesan, 1/4 cup bread crumbs, 1 tablespoon chopped parsley, 1 1/2 teaspoons lemon zest, and 1/4 teaspoon dried thyme. Drizzle in 1 1/2 tablespoons olive oil and stir with a fork until the mixture is evenly moistened.
Firmly press the Parmesan-breadcrumb mixture onto the tops of the mayo-coated salmon fillets to form an even crust.
Bake in the preheated oven until the salmon is cooked through and the topping is set, about 12 to 15 minutes. For a more golden crust, broil 1 to 2 minutes at the end, watching closely.