Ham and Cheese Crêpes Recipe

Ingredients

• 1.25 cups all-purpose flour
• 1 cup milk
• 4 large eggs
• 1 tablespoon melted butter
• 1 teaspoon butter
• 1 medium onion, thinly sliced
• 2 teaspoons butter, divided, or more as needed
• 2 tablespoons Dijon mustard
• 0.5 slice thinly sliced ham
• 8 ounces shredded Gruyere cheese