Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking dish.
Place the bacon in a skillet, and cook over medium-high heat until evenly brown. Drain on paper towels. When cool, crumble and set aside.
Place the butter in a skillet, and melt over medium heat. Stir in the ginger, onion, and mushrooms; cook until onion is transparent and tender, about 5 minutes. Remove from the heat, and mix in the Worcestershire sauce. Add salt and pepper to taste.
Stir the beans, bacon, and sour cream together in a large bowl until evenly blended.
Spread half of the green bean mixture over the bottom of the prepared casserole dish. Arrange half of the water chestnuts over the beans, then half of the Cheddar cheese, and half of the mushroom mixture. Spread the remaining green beans over the mushrooms, and repeat layers with the remaining water chestnuts, Cheddar cheese, and mushrooms. Top with the macadamia nuts.
Bake in preheated oven until top is hot and sauce is bubbly, about 30 minutes. Serve hot.