Preheat oven to 350 degrees F.
Place a large, heavy-bottom skillet over medium heat and add the oil. Once the oil is hot add the onions. Cook, stirring often, until tender, about 5-6 minutes.
Add garlic season with salt and pepper and continue to cook for 5 more minutes, or until onion starts to caramelize.
Add cabbage and cook, stirring often, until cabbage wilts, about 7 minutes. Season with salt, pepper, smoked paprika, and continue to cook for another 5 to 10 minutes until the cabbage is very tender. Remove from heat.
In a medium bowl, beat together egg yolks and eggs.
Set the springform pan on a baking sheet to allow for easy handling.
Using a pastry brush, lightly brush the bottom of the crust with some of the beaten eggs and place in the oven for 5 minutes. This will seal the crust so that it won’t become soggy when it comes into contact with the custard.
Add salt, pepper, milk, and cream to the remaining eggs and whisk together until combine.
Spread the cabbage, ⅔ of the chopped cooked bacon, and onion mixture into an even layer onto the crust. Sprinkle cheddar cheese, and green onions evenly on top.
Slowly pour the egg custard over the filling.
Place the quiche, into the prepared baking sheet, and transfer it in the oven. Bake for 30 to 35 minutes, or until set and just beginning to color on top.
Remove from oven and allow to sit for at least 10-15 minutes before slicing serving.
Garnish with green onions and serve with lemon wedges.