Heat the oven to 400°F. Cover a rimmed baking sheet with aluminum foil and lightly coat the foil with non-stick spray.
Pile the broccoli in the center of the baking sheet. Drizzle with olive oil and add the garlic, then toss everything together to coat the broccoli evenly.
Sprinkle salt and pepper over the broccoli to taste, then spread it out towards the edges of the baking sheet. Leave enough space in the center for the salmon fillets.
Season the underside of the salmon with salt and pepper, then place the fillets in the center of the baking sheet. Leave about 3/4 inch of space between each fillet to ensure even cooking.
In a mixing bowl, whisk together the mayonnaise, lemon juice, and garlic. Brush about 1/2 tablespoon of this mixture over each salmon fillet, then season the tops with salt and pepper.
In a mixing bowl, combine the Parmesan, bread crumbs, parsley, lemon zest, and thyme. Drizzle in 1 1/2 tablespoons of olive oil, then stir with a fork until the mixture is evenly moistened. Press the Parmesan mixture evenly over the tops of the salmon fillets.
Bake in the preheated oven for 12–15 minutes, or until the salmon is cooked through. For a golden crust, switch to broil for the last 1–2 minutes if desired.