Peel and slice onions to about 1/8-inch thick — thin enough to cook quickly, thick enough to avoid scorching. Yellow or Spanish onions work best. Limit to 2 large onions per 12-inch Skillet to prevent steaming. Have your fat ready and keep a splash of water, broth, or wine nearby to deglaze if needed.

Heat a Skillet over medium to medium-high heat. Add butter, oil, or a mix and let it shimmer. Add sliced onions in large handfuls, stirring for 1–2 minutes per batch until they begin to soften — this prevents overcrowding. Once all onions are in, season with a pinch of salt. Cook over medium heat, stirring every few minutes, for 8–12 minutes total until soft, translucent, and lightly golden. To speed up softening, add 1/4 to ½ cup water or broth and cover; steam wilts the onions in a few minutes. Remove the lid once liquid evaporates and continue cooking uncovered. If the pan looks dry, deglaze with a splash of water, broth, or wine, scraping up any browned bits. Don't crank the heat — high heat burns the outside before the onions cook through.

Line a Baking Sheet with Aluminum Foil, extending it up the sides to catch grease. Optionally place a Wire Rack on top for better airflow and crispier bacon. Lay strips in a single layer — close but not overlapping. No oil or extra seasoning needed.

Set Oven to 400°F. You can start bacon in a cold oven as it preheats, or wait until fully preheated — both work. Use an external Meat Thermometer if your oven runs inaccurate. Start checking at 14–15 minutes. Thin-cut: 10–14 min. Standard-cut: 15–20 min. Thick-cut: 20–22 min. No need to flip. Check every couple of minutes after the first check — overdone happens fast. Pull bacon just before it looks done; it keeps cooking for a minute or two off the heat.

Pour in the ½ cup apple cider or dry white wine and ½ cup chicken broth low-sodium, scraping up any browned bits from the bottom of the pan. Stir in the 1 tsp Dijon mustard. Simmer over medium heat until the liquid reduces by about half and the sauce is slightly thickened, about 4–5 minutes. Remove from heat and swirl in the remaining 2 tablespoons of 3 tbsp unsalted butter divided until glossy. Taste and adjust seasoning with 1 tsp kosher salt and ½ tsp black pepper freshly ground.