I've been meal prepping onions the last few weeks. Last week I noticed that I didn't manage to color the onions much and the flavor was weak relative to previous weeks. It got me curious about more intentionally caramelizing them and I found this video.

This dude's process, which according to the comments is worth it, takes ~4 hours. If you're careful, I suspect you could probably rush it with higher heat, accepting a slightly more bitter end product.

I might give this a shot tomorrow while I'm doing my other weekly chores.