Gruyere Open Face with Bacon & Apple | Bays English Muffins

Ingredients

• 1 medium onion (about 5 ounces), chopped
• 1 Tbsp. olive oil
• 1/4 tsp. salt
• 4 Tbsp. butter, softened
• 2 tsp. Dijon mustard
• 4 BAYS English Muffins, any variety, split, toasted
• 8 slices bacon, cooked, cut in half
• 1/2 red apple, cored, cut into 16 thin slices
• 2 oz, Gruyere cheese, shredded
• 1 tsp. fresh thyme leaves, optional