Authentic Zwebelkuchen ~. Bacon and Onion Pie

Authentic German Zwebelkuchen
Bacon and Onion Pie
Treat yourself to an easy but nutritious dish.  Just add a vegetable and salad and the meal is ready.  Leftovers are easily reheated.  Serves 8.
Ingredients:
For the Dough:
1 cup (240ml) warm milk (110°F/45°C)
2 1/4 tsp active dry yeast
1 tsp sugar
2 1/2 cups (320g) all-purpose flour
1 tsp salt
2 tbsp butter, softened
For the Filling:
2 lbs (900g) yellow onions, thinly sliced
6 oz (170g) bacon, chopped
2 tbsp butter
1 cup (240g) sour cream
3 large eggs
1/2 tsp ground nutmeg
1/2 tsp salt
1/2 tsp freshly ground pepper
1 tsp caraway seeds (optional)

Directions:

Prepare Dough: Activate yeast in warm milk with sugar. Mix with flour, salt, and butter, then knead until smooth. Let rise for 1 hour.

Caramelize Onions: Cook onions in butter over medium heat until golden, about 25 minutes. Cook bacon until crisp.

Prepare Filling: Whisk sour cream, eggs, nutmeg, salt, and pepper. Stir in onions, bacon, and caraway seeds.

Assemble: Roll out dough, press into springform pan, and pour filling over it.

Bake: Bake at 375°F (190°C) for 40-45 minutes until golden.