Preheat oven to 425 degrees. Line a large baking sheet with parchment.
Whisk together the brown sugar, bourbon, orange juice, soy sauce, chili powder, cinnamon, and a big pinch of salt and pepper. Pour half of the marinade over the salmon filets, turning to coat both sides. Let sit 10 minutes at room temperature.
While the salmon marinates, add the sweet potatoes to a large pot and fill with enough water to cover the potatoes. Bring to a boil and cook for 12-15 minutes until very soft. You should be able to easily pierce the potatoes with a fork. Drain the potatoes thoroughly and mash with a potato masher or fork. Stir in 1/3 cup of coconut or whole milk, brown sugar, butter, maple syrup, cinnamon, and salt and pepper to taste. If you'd like them creamier, add more milk to reach desired consistency.
Toss the Brussels sprouts on the baking sheet with 1 tablespoon olive oil, salt, and pepper. Roast for 10 minutes.
Pour the unused bourbon marinade in a small saucepan and bring to a boil. Cook until thick enough to coat the back of a spoon, about 8-10 minutes.
Remove the sprouts from the oven and push to one side of the pan. Add the salmon filets (discard the marinade). Roast for 10-15 minutes longer, until desired doneness.
Divide sweet potatoes, salmon, and sprouts among bowls. Drizzle generously with the bourbon glaze.