1 Pot, 1 Cutting board, 1 Large knife, 1 Small knife, 2 Bowls, 1 Casserole dish, 1 Whisk, 1 Mini food processor, 1 Tablespoon, 1 Measuring cups, 1 Sieve, 1 Fine grater, 1 Oven rack, 1 Rubber gloves, 1 Grater
1 Rinse nettles, shake dry and pluck leaves (wear rubber gloves to prevent stinging).
2 In a pot, bring 1-2 liters (approximately 1-2 quarts) of water to a boil and add salt. Add nettles and return to a boil. Drain and then plunge into a bowl of ice water to stop the cooking. Drain well.
3 Peel kohlrabi and sweet potatoes and reserve kohlrabi greens. Halve sweet potatoes and kohlrabi lengthwise and cut each into about 3 mm (approximately 1/8-inch) thick slices.
4 Mix the sliced kohlrabi and sweet potatoes with the nettles in a bowl. Sesaon with salt and spread in a shallow baking dish.
5 Whisk together the eggs and milk in bowl and season with salt, pepper and freshly grated nutmeg.
6 Pour egg mixture over the vegetables. Bake gratin on the middle rack of preheated oven at 200°C (fan oven 180°C, gas mark 3) (approximately 400°F/convection 350°F) for 15 minutes.
7 Meanwhile, chop rye bread in a mini food processor until fine crumbs. Grate the cheese and mix with the crumbs.
8 Sprinkle crumb mixture over the gratin. Continue baking until golden brown and bubbling, about 40 minutes. Top with reserved kohlrabi greens before serving.