Using a mandoline, cut 2# new red or other waxy potatoes into 1/16"-thick slices, Place potatoes in a bowl of cold water; set aside. Heat 1/4 c canola oil in a 12" cast-iron or nonstick skillet over medium heat. Add 3 strips smoked bacon cut into 1/2" slices and cook, stirring, until its fat has rendered, about 6 minutes. Drain potatoes in a colander; add to the skillet. Season with kosher salt and freshly ground pepper to taste. Cover the skillet and cook, stirring occasionally and crushing potatoes into small chunks with a wooden spoon, until potatoes are tender, 20-25 minutes. Add 8 oz. grated cantal or gruyere cheese, 8 oz farmers' cheese, and 1 minced clove garlic to skillet; stir to combine. Reduce heat to medium-low; cover. Cook, scraping bottom of skillet with a wooden spoon, until cheese is melted and the potatoes are mashed, about 5 minutes. Stir vigorously and season with salt to taste. Sprinkle with 2 T finely chopped chives and pepper to taste.