Combine in a bowl the filling ingredients. The egg, cream, salt, black pepper, Italian seasoning, mustard, and half of the grated cheese. Keep aside.
Preheat oven to 350° F/ 180° C.
Arrange sliced potatoes in a casserole baking dish.
Pour mixed filling over the potatoes and spread it out.
Sprinkle the remaining half of the grated cheese over the filling and potatoes.
Bake for about 30 mins at 350° F/ 180° C. uncovered until golden.
Serve up hot.
Video
Notes
Use table cream, half and half, or whipping cream. Half and half contain fewer fats but the table and whipping cream would be more suitable because the fat quantity can help in binding better with the other ingredients.
Dijon mustard is optional but I recommend that you add it because it adds great flavors to the dish and mustard is an emulsifier and it will blend and bind better with the other ingredients.