Heat a large soup pot over medium low heat. Add the bacon slices flat into the pot and cook, turning a couple times, until crispy and most of the fat has drained from the bacon. This will take 8-12 minutes. Once crisp, use tongs to move the bacon to a paper towel lined plate.
To the pot with bacon fat, all the chopped onions, 2 teaspoons of salt and 1 teaspoon of pepper. Cook, stirring often, until the onions are translucent. About 10-12 minutes.
Add in the chopped potatoes, cauliflower, and chicken stock. Cover and bring to a boil over high heat.
Once boiling, reduce heat to a strong simmer and cook, stirring occasionally, until the potatoes are fork tender. About 15-20 minutes.
Puree the soup using either a blender in batches (that's what I did), or an immersion blender.
Season with additional salt and pepper, if needed.
Scoop into a bowl and garnish with crumbled bacon, cheese, sour cream, chives.