Slice onions thinly and evenly
Heat a skillet over medium-low heat
Add butter, oil, or a mix of both
Add the onions and stir to coat
Sprinkle with a small pinch of salt
Cook slowly, stirring every few minutes
Lower heat if onions start to brown too quickly
Add a splash of water if the pan gets too dry
Continue cooking until onions turn deep golden brown
Cook until soft, sweet, and jammy
Remove from heat and use as desired