"I made this Christmas morning and loved it. The cider sauce really put it over the top for me. It's a nice change from my usual sausage and egg concoction! Bonus: I have extra wild rice for my dinner! Serve the cider sauce warm with the casserole for that wonderful sweet-salty flavor combination!"
Preheat oven to 350 degrees F (175 degrees C). Grease a 2 1/4-quart casserole dish.
Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Remove bacon slices to a plate lined with paper towel to drain.
Pour most of the bacon drippings from the skillet. Melt 1 tablespoon butter in the skillet with the drippings. Saute mushrooms and onion in the butter mixture until onion is golden brown, 5 to 7 minutes. Remove from heat and scrape into a bowl to cool.
Beat eggs and half-and-half together in a large bowl until smooth. Crumble bacon into the egg mixture; add mushroom mixture, wild rice, Swiss cheese, croutons, Monterey Jack cheese, salt, black pepper, and nutmeg. Pour the egg mixture into the prepared casserole dish.
Bake in preheated oven until a toothpick inserted into the center of the casserole comes out clean, 40 to 50 minutes.
Beat apple cider, sugar, cornstarch, lemon juice, and cinnamon together in a saucepan until smooth; bring to a boil and cook for 2 minutes. Remove saucepan from heat, add 2 tablespoons butter, and stir until butter is melted smoothly into the liquid. Serve with the casserole.