1. Preheat oven to 450 degrees Fahrenheit and line a baking sheet with parchment paper.
2. In a bowl, toss Brussels sprouts with melted butter, salt, and pepper.
3. Transfer Brussels sprouts to the prepared baking sheet; arrange in a single layer and bake for 15 minutes, stirring twice during cooking.
4. In the meantime, cut the salmon down the center until you hit the skin, then butterfly it open.
5. Melt the butter in a microwave-safe bowl and add honey, mustard, and sour cream.
6. Blend until smooth and fully combined.
7. Stir in the minced garlic.
8. Remove the baking sheet from the oven and add the salmon fillets.
9. Spread the sauce over the salmon fillets and bake for 15 minutes.