Sauté the aromatics: In a large skillet over medium heat, melt the butter.
Add the shallot and a pinch of salt. Cook 3–4 minutes until soft and glossy. Stir in the garlic and cook 30–60 seconds, just until fragrant.
Bloom the miso: Reduce heat to medium-low.
Add the miso to the pan and mash it into the butter and aromatics. Let it warm gently for about 30 seconds to open up the flavor.
Add beans and liquid: Tip in the drained butter beans. Pour in 3/4 cup broth and stir to coat.
Simmer 3–5 minutes so the beans soak in the sauce.
Make it creamy: Stir in the cream (or coconut milk). If you prefer a looser sauce, add more broth a splash at a time. Taste and season with black pepper and a tiny pinch of salt.
Remember: miso is salty, so go easy.
Brighten it up: Add lemon zest and a squeeze of juice. Start with half the lemon, then adjust. The sauce should taste savory and lively, not sharp.
Add greens (optional): Stir in spinach or thinly sliced kale.
Cook 1–2 minutes until wilted and tender.
Finish with herbs and heat: Sprinkle in chopped parsley or chives. Add a pinch of red pepper flakes if you like a little warmth.
Serve your way: Spoon over toast, rice, or pasta. Drizzle with olive oil, crack on more black pepper, and finish with a dusting of Parmesan or nutritional yeast if using.