Preheat the oven to 425°F.
Pat the salmon fillets dry with a paper towel and season lightly with salt and pepper. Arrange them in a baking dish or on a sheet pan.
In a small bowl, stir together the mayonnaise, Dijon mustard, lemon zest, lemon juice, dill, Parmesan, garlic powder, salt, pepper, and honey (if using).
Spread a thick, even layer of the topping over each fillet, then sprinkle a little extra Parmesan over the top.
Bake for 10–14 minutes, depending on the thickness of the salmon, until it flakes easily with a fork.
Switch the oven to broil and cook for 1–2 minutes, watching closely, until the topping is golden brown and bubbly.
Finish with fresh dill, a little lemon zest, and a squeeze of lemon juice. Serve warm.