For the casserole:
6 large potatoes
1 cup vegetable oil
3 ½ tablespoons butter
2 tablespoons olive oil
2 onions, peeled and finely diced
1 carrot, peeled and finely diced
1-pound ground lamb or ground beef, lean
1 bay leaf
1 cup beef stock
1 teaspoon Worcestershire sauce
1 tablespoon tomato purée
For the topping:
2 cups bechamel sauce
3 ½ ounces cheddar and mozzarella cheese mix
Make the potatoes: First, peel and finely slice the potatoes lengthways into long, thin slices. It may help to use a mandoline to make sure all the potato slices are the same thickness.
In a large frying pan, heat the vegetable oil until it reaches 250 degrees. Then, cook the potato slices, in batches, until cooked through. Remove, and drain on a paper towel.
Make the meat filling: In a saucepan over medium heat, add the butter and olive oil. Next, add the onion, carrot, and bay leaf, cook until they have softened. Add the ground lamb or beef, and sauté until browned. Season with salt and pepper, and then pour in the beef stock, Worcestershire sauce, and tomato purée. Season and bring to the boil, then reduce the heat. Leave to simmer for 20 to 30 minutes, stirring occasionally.
Once cooked, the finished meat mixture shouldn’t be wet at all. If it’s still a bit liquidy after 30 minutes, turn up the heat, and allow to come to a boil for a few minutes. Remove from heat, and set aside to cool.
To assemble: Add a piece of Saran wrap over a small bowl and place potato slices in a circle, overlapping them in a fan shape. Make sure there are no holes.
Add a small spoonful of the meat filling in the center of the potato circle, and then begin to bring the potato slices up around the filling. Pull the Saran wrap up and around the potato to seal, and then place the stuffed potato bomb on a plate. Repeat this step until all the filling is used. Place the potato bombs in the fridge for at least 30 minutes.
Preheat the oven to 350 degrees.
When ready to cook, unwrap the bombs from the Saran wrap. In a baking dish, place the potato bombs, and ensure they fit tightly together. Pour the bechamel sauce on top, and sprinkle the cheese.
Place in the oven, and bake for 20 minutes until the cheese is golden and bubbling.
Serve straight away, and enjoy.