01 -
In a large stainless steel sauté pan or two large skillets, melt butter over medium-high heat until foaming.
02 -
Add onions and cook, stirring occasionally, until softened, about 8 minutes.
03 -
Lower heat to medium-low and cook, stirring frequently, until onions become very sweet and rich golden-brown, 1 to 2 hours. Add 1 tablespoon water whenever browned bits on bottom threaten to burn, scraping up the fond.
04 -
Season with salt and pepper to taste.