Preheat the oven to 350°F. Lightly spray a 8x12-inch baking dish with cooking spray.
In a large mixing bowl, sift together the flour, mustard powder, and salt. Add the butter and mix until the mixture is crumbly.
1 ½ cups all-purpose flour, ½ tablespoon ground mustard, ½ teaspoon salt, 4 tablespoons butter
In a separate bowl, whisk together the milk and eggs. Pour into the flour mixture and stir until well combined.
3 cups milk, 3 large eggs
Add the onion, cheddar, and ham to the batter. Mix until evenly distributed.
1 small onion, 1 ½ cups cheddar cheese, 1 ½ cups cooked ham
Transfer the mixture to the prepared baking dish and sprinkle parsley over the top.
1 handful fresh parsley
Bake for 1 hour, or until puffed and golden brown.
Notes
🥡 STORAGE: Store leftovers in an airtight container in the refrigerator for up to 3 days.Cover the baking dish tightly with foil or plastic wrap if storing directly in the dish.♨️ REHEATING:Oven: Preheat to 325°F and bake covered for 15-20 minutes, until heated through.Microwave: Heat individual portions for 1-2 minutes.Skillet: Warm slices in a nonstick skillet over medium heat for a few minutes per side.❄️ FREEZING: Cool completely, then wrap tightly in plastic wrap and foil, or place in a freezer-safe container.Freeze for up to 2 months.Thaw overnight in the refrigerator before reheating.💡 TIPS FOR BEST RESULTS: Use freshly grated cheddar cheese for the best melt and flavor.Make sure the butter is softened, not melted, to get the right crumbly texture when mixed with flour.Let the bake rest for 5 minutes before slicing to help it set.🍳 ALTERNATE COOKING METHODS: No alternate cooking methods are recommended for this recipe. It bakes best in the oven.♻️ LEFTOVERS: Slice into portions and enjoy reheated for breakfast, lunch, or dinner.Leftovers make an excellent filling for wraps or sandwiches.📝 NOTES: Add chopped bell peppers or spinach for extra color and flavor.Replace part of the ham with cooked bacon for a smokier taste.Serve with hot sauce or salsa for a little kick.Serve with fruit, salad, or roasted potatoes to make it a complete meal.