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.

Add the 2 lb Yukon Gold potatoes peeled and cut into 1-inch chunks chunks, 5 cups chicken broth low-sodium; or vegetable broth for vegetarian, 1 tsp 3 tbsp unsalted butter, and ¼ tsp white pepper freshly ground; or black pepper. Stir to combine and bring to a boil over high heat. Reduce the heat to medium-low, cover, and simmer until the 2 lb Yukon Gold potatoes peeled and cut into 1-inch chunks are completely tender and easily pierced with a fork, about 20 minutes.

Remove the Pot from the heat. Use an Immersion Blender to blend the soup until smooth and creamy. Alternatively, carefully transfer the soup in batches to a countertop Blender and blend until silky, then return to the Pot. For a chunkier texture, blend only half the soup.

Return the Pot to low heat and stir in the ½ cup heavy cream or half-and-half for a lighter version. Taste and adjust seasoning with additional 3 tbsp unsalted butter and ¼ tsp white pepper freshly ground; or black pepper as needed. Heat gently for 2–3 minutes until warmed through — do not boil after adding the ½ cup heavy cream or half-and-half for a lighter version.