Silky lemon‑Parmesan sauce cloaks tender butter beans and spinach, enriched with cottage cheese for a bright, satisfying, high‑protein one‑pot meal ready in 30 minutes.
Melt 1 tablespoon butter in a large skillet or Dutch oven over medium heat.
Cook 1 large yellow onion until golden around the edges, about 5 minutes.
Add 2 cloves minced garlic and cook, stirring frequently, 1 to 2 minutes.
Stir in 3 tablespoons all purpose flour to coat.
Whisk in 1 cup vegetable stock, 2 teaspoons yellow mustard, and 1 teaspoon fine sea salt until smooth.
Bring to a gentle simmer and cook, stirring occasionally, 2 to 3 minutes until slightly thickened.
Stir in 1/3 cup whipping cream and 1/3 cup grated Parmesan cheese until smooth.
Add 3 cans butter beans and reduce heat to medium-low; cook, stirring occasionally, about 10 minutes for flavors to meld.
Stir in 2 cups cottage cheese and 1/4 cup fresh lemon juice; allow the mixture to return to a gentle bubble (sauce will thin slightly).
Stir in 3 cups baby spinach just until wilted.
Season with black pepper to taste (and more salt if needed).
Serve hot, optionally with crusty or grilled bread and extra Parmesan or chopped parsley.