Preheat the oven to 350 degrees Fahrenheit.
Heat the oil in a pot over medium high heat. Add the finely chopped onion and ½ teaspoon sea salt. Saute until tender, translucent, and beginning to leave brown flecks on the pan, 4-5 minutes, stirring frequently. Add the minced garlic and cook for 10 to 15 seconds, just until fragrant, stirring constantly. Add half of the rosemary (reserving the rest for later) and cook for 5 to 10 more seconds.
Add about half a cup of stock, and deglaze the pan by scraping all the nice browned bits into the stock with a wooden spoon. Then add the rest of the stock, along with the bay leaf (crumple it slightly first) and the diced potatoes.
Bring the soup to a simmer and cook until the potatoes are tender, about 30 minutes.
Meanwhile, make garlic chips by thinly slicing the remaining cloves of garlic. Coat them in olive oil, sprinkle with salt, arrange on a parchment paper-lined baking sheet, and bake at 350 degrees Fahrenheit until golden, about 10 minutes (keep a close eye on them!).
When the potato pieces in the soup are tender, mash about half of them to thicken the stock. You can use either a potato masher or just the back of a wooden spoon.
Divide the soup into bowls, and garnish each with 1 teaspoon balsamic vinegar, 2 tablespoons of creme fraiche, ½ teaspoon of minced rosemary, and a few garlic chips.