Ham & Cheese Oven-Puffed Pancake - Once Upon a Chef

Ingredients

• 3 large eggs
• 1 tablespoon Dijon mustard
• Heaping ½ teaspoon salt
• ¼ teaspoon freshly ground black pepper
• 1 cup all-purpose flour, spooned into a measuring cup and leveled-off
• 1¼ cups whole milk (or substitute ¼ cup heavy cream + 1 cup skim milk)
• ⅔ cup grated Gruyere cheese
• 1 tablespoon finely chopped fresh chives
• 3 tablespoons unsalted butter
• 5 slices (4 oz) thinly sliced ham, finely diced