1. Make the clarified butter: In a large heavy-bottomed pot set over medium-low heat, melt 10 sticks of the butter, spooning off and discarding the white foam that rises to the surface as the butter melts. (Skip this step if using duck fat.)

2. Once the butter is completely melted and all of the white foam has been skimmed off, increase the heat to medium and warm the clarified butter (or duck fat) until it is hot but not simmering. Add the potatoes, garlic, thyme and peppercorns. Season with salt and pepper and bring to a simmer. Cook the potatoes until tender, never boiling the fat, for about 20 minutes.

3. Meanwhile, heat a large skillet over medium-high heat. Add the vegetable oil and the bacon and cook, turning the pieces once midway through cooking, until the bacon becomes crisp on all sides, about 10 minutes. Use a slotted spoon to transfer the potatoes to the skillet and cook until browned and crisp, about 7 minutes. Pour off the excess fat and add the chicken broth and the remaining 1 tablespoon of butter. Toss to coat and season with salt and pepper. Divide among four plates, top each with some crème fraîche and chives and serve.