Heat the butter in a medium saucepan over medium-high heat. Once it's melted, add the mushrooms and cook for 10 minutes, stirring occasionally.

Stir in rosemary and milk. Bring the mixture to a simmer, and reduce heat to medium-low.

In a small bowl, whisk eggs together. Carefully transfer a little of the warm milk to the eggs and whisk together until the eggs are warmed.

Add the oats, salt, paprika, garlic powder, black pepper, and cayenne pepper to the milk/mushroom mixture. Stir well.

Pour the warmed egg mixture into the oat mixture, stirring constantly.

Cook for about 10 minutes, stirring constantly until almost all of the liquid has evaporated and the oats are cooked.

Remove from heat and stir in shredded Swiss cheese and green onions.

Serve in bowls and sprinkle with bacon if desired. Enjoy!