Pluck the small leaves from the stem ends of the kohlrabi and cut into narrow strips, then remove the skin from the kohlrabi and cut diagonally with a vegetable slicer about 3 mm thick slices. Sauté the slices in butter in a saucepan with as large a diameter as possible, stir thoroughly, pour in the whipping cream and stir well, season everything together with salt, pepper and a small amount of freshly grated nutmeg, add the kohlrabi flakes. Steam the vegetables in the open saucepan for 5 min at low temperature until soft, then cool a little bit. Cut the basil leaves diagonally into thin strips and mix with the kohlrabi.
Preheat the oven to 180 °C. Now layer the kohlrabi evenly on a shallow tart pan or in a shallow gratin dish and top evenly with the mozzarella cut into very thin slices. The gratin needs about half an hour, if the cheese is not brown yet, you can help it with the broiler at the end.
In the meantime, prepare the brown rice. To do this, you need 2.5 times the mass of water in relation to the long grain rice, for example 1 cup of long grain rice and 2.5 cups of water. To begin, bring the water to a boil and season with enough salt that it actually tastes slightly salty. Next, add in the long grain rice, bring to a boil once, and then cook at a very low temperature with the lid closed.