Place the broccoli in a large pot about 2 cm. Of water at the bottom. Bring to a boil and cook for 7 minutes. Drain and pull the broccoli onto the dish.
Melt the butter in a small skillet over medium heat. Combine brown sugar, soy sauce, vinegar, pepper and garlic. Bring to a boil, then remove from heat.
Mix with cashews and pour in broccoli sauce. Serve immediately.