Heat the olive oil in the large Dutch oven over medium-high heat. Add the sausage coins in a single layer and brown 2–3 minutes per side, until deeply golden at the edges. Transfer to a plate — they'll go back in at the end.

Reduce the heat to medium. Add the onion to the same pot and cook 3 minutes, stirring, until softened. Stir in the garlic, sage, salt, pepper, and nutmeg; cook 1 minute, until intensely fragrant.

Add the butternut squash and chicken broth. Bring to a boil over high heat, then reduce to a steady simmer. Cook 12–14 minutes, until the squash cubes are completely fork-tender — they should offer no resistance.

Take the pot off the heat. Use the immersion blender to blend about half the soup — 4–5 quick pulses — leaving plenty of squash chunks intact. (No immersion blender? Mash with a potato masher, or transfer 2 cups to a countertop blender, blend smooth, and stir back in.)

Return the pot to medium heat. Stir in the cannellini beans and kale; simmer 3–4 minutes, until the beans are heated through and the kale is wilted and silky.

Stir the browned sausage coins back in and simmer 1 minute to heat through. Off the heat, stir in the apple cider vinegar — it brightens everything. Taste and add more salt if needed. Ladle into bowls and top with parmesan; serve with crusty bread.