Dissolve the dried yeast and sugar in some of the luke warm milk and allow to sit until bubbly, about 5 minutes.
1 teaspoon sugar, 155 milliliters milk, 4 grams active-dry yeast
Add the remaining dough ingredients and knead for 5 minutes. Cover the bowl and allow the dough to rise in a warm spot until doubled in size, 1 to 1 ½ hours.In the meantime, rub your baking dish with soft butter. 250 grams all-purpose flour, 55 grams butter, 1 teaspoon salt
While the dough rises, trim and peel the onions and cut them up into rings or half rings.
500 grams yellow onions
Over medium heat and in a large skillet, cook the onion with the butter until they are clear and soft. You don't want to brown them. This can take 10 minutes or longer. Add the flour and let the mixture cool down. Season with a good amount of salt.
55 grams butter, 1 Tablespoon all-purpose flour
Whisk together the eggs and cream. Add caraway if desired (you can also sprinkle it on top instead).
2 large eggs, 100 milliliters heavy cream, 1 teaspoon caraway seeds
Press down the dough evenly in the baking pan using your hands and fingers, going up about one inch or two centimeters on the sides. No tools needed!Note: My quiche pan has a 9.5-inch diameter, but if yours is larger, your Zwiebelkuchen just won't be quite as tall. Add the cooked onions to the baking dish and top with the egg-cream mixture. Sprinkle the caraway seed on top (or add to the filling). Evenly distribute the cut-up bacon on top.
2 slices bacon
Bake on the middle rack at 390° F (200° C) for 35 to 45 minutes. Gentle wiggle your baking dish. The middle should not shake when it's fully baked and the crust should be nice and golden in color.
Allow cooling for at least 10 minutes before serving. Serve warm with Federweißer (a young German wine) or some good Riesling and a green salad on the side. Guten Appetit!