Beef and Potato Casserole

Ingredients:

• 2 1/2 to 3 cups diced roast beef
• 1/2 cup chopped onion
• 1 cup beef gravy or prepared brown gravy
• 2 tablespoons dry white wine
• 1/4 teaspoon dried thyme, crumbled
• 1/4 teaspoons dried rosemary, crumbled
• dash garlic powder
• 1/2 to 1 teaspoon salt, or to taste
• 1/4 teaspoon ground black pepper
• beef broth or water, if needed
• 2 cups prepared mashed potatoes, seasoned
• 2 tablespoons butter
• 1 egg
• 1/2 to 1 cup shredded Cheddar cheese

Preparation: