This was done with leftover squash from last night but if you don't have leftovers, cook some ahead of time and let it cool. Remove the water either by squeezing the hell out of it between wads of paper towel or, as I did, put it through a potato ricer.

Take a 12" skillet (cast iron works best but isn't necessary) and melt 2T of unsalted butter over medium high heat. Add half of a red onion, finely diced and sweat without letting the onion brown. Add a couple handfuls of drained squash, mix to coat in butter and distribute onion, then spread out and compact. Sprinkle with kosher salt and drizzle with olive oil. Brown, flip, brown, serve.

It's basic hash brown technique. If you've never done it before, just practice. You'll get it.