1 tablespoon butter
1 tablespoon olive oil
8 fresh sprigs thyme, stripped and chopped
1/2 onion, finely chopped
1/2 serrano chile pepper, seeded and finely chopped
Pinch salt
Grind or two freshly ground black pepper
8 button mushrooms, sliced
1 teaspoon Worcestershire sauce
1/2 teaspoon salt
A few grinds freshly ground black pepper
1 clove garlic, grated on a rasp
8 ounces ground chuck
Two 7-to-8-inch-round flatbreads, such as Aladdin or Metsuyan
3 slices American cheese
4 strips bacon, cooked and chopped
4 ounces smoked mozzarella, sliced or torn into bits
Ketchup, for serving