Ingredients:

  • 2 lbs (900 g) Russet or Maris Piper Potatoes, peeled and sliced 1/4 inch thick
  • 3 cups (450 g) Leftover Cooked Ham, diced
  • 4 tbsp (60 g) Unsalted Butter
  • 1/4 cup (30 g) All-Purpose Flour
  • 2 cups (475 ml) Whole Milk, warmed slightly
  • 1/2 cup (120 ml) Low-Sodium Chicken Stock
  • 1 tsp (5 ml) Dijon Mustard
  • 1 tsp (5 ml) Fresh Thyme leaves, finely chopped
  • 1/2 tsp Kosher Salt (adjust based on ham saltiness)
  • 1/4 tsp Freshly Ground Black Pepper
  • 2 cups (225 g) Mature Sharp Cheddar, grated (divided)
  • 1 cup (115 g) Gruyère or Emmental, grated
  • 1/4 cup (30 g) Panko Breadcrumbs (optional, mixed with 1 tbsp melted butter)

Instructions:

  1. Pre-cook the Potatoes: Place the sliced potatoes in a large pan and cover with cold, salted water. Bring to a boil and cook for 5–7 minutes, or until just tender but still firm (al dente). Drain thoroughly and set aside. Preheat oven to 375°F (190°C) and lightly grease the 9x13 inch casserole dish.
  2. Make the Roux: In a large saucepan, melt the 4 tbsp of butter over medium heat. Whisk in the flour and cook, stirring constantly, for 1–2 minutes until the mixture forms a paste and smells slightly biscuity.
  3. Add Liquids: Slowly pour in the warm milk, whisking vigorously the entire time until the mixture is smooth and lump-free. Once incorporated, stir in the chicken stock.
  4. Thicken and Flavour: Bring the sauce to a gentle simmer, stirring constantly, until it thickens sufficiently to coat the back of a spoon (about 5–7 minutes). Remove from the heat.
  5. Season and Add Cheese: Stir in the Dijon mustard, thyme, salt, and pepper. Incorporate 1.5 cups (170g) of the grated sharp cheddar and all of the Gruyère. Stir until the cheese is completely melted and the sauce is uniform and smooth. Taste and adjust seasoning.
  6. Combine Ingredients: Gently fold the pre-cooked potato slices and the diced ham into the prepared cheese sauce. Ensure everything is well coated.
  7. Fill the Dish: Pour the potato and ham mixture into the prepared casserole dish, spreading it out evenly.
  8. Prepare Topping: Sprinkle the remaining 1/2 cup (55g) of sharp cheddar evenly over the top. If using, mix the Panko breadcrumbs with a tablespoon of melted butter and scatter them over the cheese for extra crunch.
  9. Bake: Place the dish in the preheated oven and bake for 35–40 minutes. The casserole should be bubbling hot around the edges, and the top should be golden brown and crusty.
  10. Rest: Remove from the oven and let the casserole rest for 5–10 minutes before serving. This allows the sauce to set properly.