Grease a 9x13 baking dish lightly with butter or cooking spray. Spread cubed English muffins evenly inside the dish. This layer creates the soft and hearty base for the casserole.

Sprinkle diced ham over the muffin cubes evenly. Add shredded cheddar cheese and green onions on top. The ham gives savory flavor while the cheese adds creamy richness to every bite.

In a large bowl, whisk eggs, milk, heavy cream, salt, black pepper, onion powder, and garlic powder together. Mix until smooth and well combined. This mixture makes the casserole soft and fluffy.

Pour the egg mixture slowly over the casserole layers. Press gently so the bread absorbs the liquid evenly. Cover the dish and refrigerate for at least one hour before baking.

Preheat the oven to 350 degrees Fahrenheit. Bake the casserole for about 40 minutes until golden and firm. The center should look set and the top should have light browning.

Whisk egg yolks, melted butter, lemon juice, paprika, and salt together in a saucepan over low heat. Stir constantly until smooth and slightly thickened. Avoid high heat to prevent curdling.

Remove the casserole from the oven carefully. Let it rest for five minutes before slicing. Drizzle warm Hollandaise sauce over each serving and enjoy this comforting breakfast casserole fresh and warm.