Place the broccoli into a large pot with about 1 inch of water in the bottom.
Bring to a boil, and cook for 7 minutes, or until tender but still crisp; drain, and arrange broccoli on a serving platter.
While the broccoli is cooking, melt the butter in a small skillet over medium heat.
Mix in the brown sugar, soy sauce, vinegar, pepper and garlic.
Bring to a boil, then remove from the heat.
Mix in the cashews, and pour the sauce over the broccoli.
Serve immediately.