Arrange muffin pieces, crust sides down, in an 8-inch square baking dish coated with cooking spray; drizzle with butter. Arrange ham and next 4 ingredients (ham through garlic) over muffin pieces.
Combine nutmeg and remaining ingredients in a bowl; stir well with a whisk. Pour over muffin mixture. Cover; chill 8 hours or overnight.
Preheat oven to 375°.
Uncover strata; bake at 375° for 50 minutes or until set. Let stand 10 minutes.