Remove the outer large leaves from each tuber, set aside 5 of them. Put the kohlrabi in the boiling salted water so that the heart leaves are not covered with water, soften for about twenty-five minutes. Set kohlrabi broth aside.
Cut a lid including the heart leaves and a small bottom of each kohlrabi into small pieces, scoop out with a spherical cutter except for a 5 mm thick rim. Keep the kohlrabi lids, balls and hollowed-out kohlrabi warm in the remaining cooking juices in the frying pan with the lid closed.
Stuffing: heat oil and butter, sauté garlic and kohlrabi leaves. Add long-grain rice, stirring to soften until translucent. Add wine, cook completely.
Gradually pour kohlrabi broth into long-grain rice, stirring frequently, so that it is always just covered with liquid. Simmer gently for about twenty minutes until long grain rice is creamy and al dente. Remove the frying pan from the plate.
Mix the cheese into the risotto. Fill the risotto into the warm kohlrabi, put the lids on, arrange in deep plates with the cut out balls.
Serve with: grilled meat.