Thaw the frozen hash browns and squeeze out excess moisture. Combine with shredded white cheddar, salt, and black pepper. Press into a greased springform pan and freeze for 1 hour.

Preheat oven to 425°F. Once the crust is set, bake for about 15 minutes until edges are golden. Cool slightly.

Melt butter in a skillet over medium heat. Sauté diced onions for 10-15 minutes until caramelized. Set aside to cool.

Whisk together eggs and heavy cream in a large bowl. Stir in cheddar cheese, caramelized onions, crumbled bacon, and season with salt and pepper.

Pour filling into pre-baked crust. Lower oven to 375°F and bake for 25-30 minutes until filling is set.

Check quiche after 25-30 minutes, loosen edges with a knife, and return to oven for an additional 10-15 minutes for a crispier crust.

Let cool for 10 minutes before slicing. Garnish with chopped chives and serve.