Add stock + water, bring to a gentle simmer, stir, then cook ~25 minutes, stirring occasionally until creamy but with a little bite.
Greens & garlic
3 In a separate pan, sauté garlic briefly in a bit of butter or oil, add greens, and cook until wilted and tender. Season with salt/pepper.
4 Or just throw chopped greens into the oats for the last 5–10 minutes if you want it one-pot.
Enrich
5 Off heat, stir in cheddar (and parm if using) + remaining butter. Adjust consistency with a splash of cream or hot water.
Season
6 Taste for salt and lots of black pepper.