How to Make It
In a skillet, melt 1 tablespoon of the butter. Add the garlic and cook over low heat until fragrant, 1 minute. Add the curry powder and cook, stirring, until fragrant, 1 minute. Scrape the mixture into a bowl and let cool. Stir in the remaining 3 tablespoons of butter and the parsley and hot sauce. Fold in the bread crumbs and season with salt and pepper.
In a large pot, bring 1 cup of water to a boil. Add the mussels, cover and cook over moderately high heat, shaking the pot a few times, until the mussels open, 3 minutes. Using a slotted spoon, transfer the mussels to a large rimmed baking sheet. Let cool, then break off 1 shell of each mussel. Pry each mussel loose, leaving it in the shell. Spoon a little of the mussel cooking liquid over each mussel.
Preheat the broiler. Dot each mussel with 1 teaspoon of the bread crumb topping. Broil the mussels 6 inches from the heat, rotating the pan a few times, until the crumbs are browned and crisp, 2 minutes. Serve.