Martha'S Scalloped Mushrooms - cooking recipe

Ingredients

9 tablespoons unsalted butter
1 (1 lb) bag frozen pearl onions, thawed and drained
3 lbs assorted mushrooms, trimmed and cut in half, large ones should be quartered (white, cremini, shitake, etc.)
3/4 cup heavy cream
1 cup freshly grated parmesan cheese
1 teaspoon salt
1/4 teaspoon fresh ground pepper
1 cup coarse plain breadcrumbs, preferably homemade

Preparation

Preheat oven to 350. Heat 1 tablespoon butter in a large oven-proof skillet over medium-high heat. Add onions, and cook until soft and just starting to brown - about 5 minutes. Transfer to a large mixing bowl.
Working in four batches, melt 2 tablespoons butter in same skillet; add one quarter of the mushrooms, tossing to coat evenly with butter. Cook until mushrooms have released their juices and most of the juices have evaporated, about 5 minutes. Transfer to bowl with onions. Repeat process with remaining butter and mushrooms.
Add heavy cream, 1/2 cup Parmesan, salt, and pepper to bowl; stir until combined. Return the mixture to skillet or transfer to a large baking dish. Sprinkle breadcrumbs and remaining 1/2 cup Parmesan over the top.
Bake until bubbling and nicely golden on top, about 25 minutes. Remove from oven. Serve hot.
This could probably be made up ahead of time and then refrigerated until needed. Adjust baking time accordingly.