Preheat the oven to 200 C / Gas 6. Grease a 20cm pie dish.
In a bowl, mix the breadcrumbs with half a beaten egg. Then mix in the sausage meat, onion, garlic and seasoning. Press into the base and sides of the prepared pie dish with the back of a fork. Brush with a little beaten egg.
Bake in the centre of the oven for 20 minutes, or until the sausage is no longer pink. Remove from the oven.
Reduce the oven temperature to 180 C / Gas 4.
Into a saucepan over a medium heat, warm the spaghetti in tomato sauce. Pour the sauce into a separate bowl and mix with the remaining egg. Return the sauce back to the spaghetti and stir gently over a low heat until thickened. Pour the spaghetti into the baked sausage and breadcrumb case.
Bake in the centre of the oven for 20 minutes until bubbling. Remove from the oven and sprinkle the top with cheese.
Pop under the grill and cook until the cheese is melted and golden brown. Remove from the heat and serve.