In a large wok or skillet over medium heat, add the oil, garlic, ginger, and shallot. Sauté for 3-4 minutes.
Add in 2 tablespoons of butter and the brown sugar. Stir until combined. Add the sriracha, soy sauce, and chili peppers. Let simmer, stirring frequently, for 2-3 minutes.
Add the last two tablespoons of butter and stir until it is melted and incorporated.
Toss the crab clusters with the sauce mixture and top with lots of freshly chopped scallions. Serve hot.