Combine Extra Melt Yellow Cheese Sauce, Swiss cheese and hot water in large saucepan; whisk until smooth. Cook over low heat, whisking occasionally, until smooth and heated through. Hold warm for service.
Melt Clarified Butter in large sauté pan; add mushrooms. Sauté until softened; set aside.
Add spinach to same pan; sauté until just wilted.
Layer spinach, mushrooms and tomato slice on each English muffin half. Top each with 1 poached egg. Spoon 2 ounces Swiss cheese sauce over each egg. Serve immediately.