Season the ground beef with salt, pepper, and Beaver Brand Cream Style Horseradish.
Form into 4 hamburger patties. Melt 1 tbsp of butter into a pan and cook to desired done-ness.
Meanwhile, melt the remaining 1 tbsp of butter in a separate skillet. Add the onions and sauté until soft and golden-brown.
Mix all of the Horseradish Cream Sauce ingredients together until smooth.
Place the hamburger patty onto the bottom half of the roll or bun. Top with sauteed onions and your choice of additional toppings (cheese, lettuce, tomato, etc.). Spread the Horseradish Cream Sauce onto the top half of the roll or bun.