Put the mince beef, the spices, the egg, the bread crumbles and the milk in a bowl and mix together.
Let the mince meat rest for 10 minutes.
Cut the ham in thin slices, or you can use already thin sliced ones.
Now it is time to continue with the mince beef. Divide the mined beef in to 4 equal pieces.
Press the mince beef in to 4 round hamburger, you can do it with a hamburger press or by hand.
Put the hamburgers and the hamburger bread on the BBQ, and grill them for approx 15 minutes in total for both sides. Make sure to get a nice and crispy surface, but not so it will be burn.
Take away the bread before the hamburger and start to prepare the bread with the ham, cheddar cheese, mushrooms, sour cream and the arugula.
At last place the hamburger between the hamburger bread, and it is ready to serve.