Preheat oven to 450 degrees.

In a skillet melt 2 tablespoons butter and then add squash, onions, salt, and pepper. Stir and cook on medium for 1 minute and then cover and cook 2-3 minutes more until the squash is softened but still crisp. During the last minute, add the garlic and stir until fragrant.

Add the cream and stir, cooking until thickened a little, about 3 or 4 minutes. Remove from the heat and add the cheese and 1/4 cup of bread crumbs and stir to mix. Pour into a 9 x 9-inch (or equivalent size) greased casserole dish. Top with the remaining bread crumbs and melt the last tablespoon of butter and drizzle over the top of casserole.

Bake uncovered for 10 minutes or until golden brown.