Step 4: Slow Cook
Cover and cook on Low for 2–3 hours, checking at 2 hours. Stir gently halfway through to ensure even cooking. Pasta is done when tender.
Step 5: Add Spinach
Fold in the fresh baby spinach; the residual heat will wilt it in about a minute. If the sauce seems too thick, stir in a splash of extra broth.
Step 6: Finish and Serve
Taste and adjust seasoning. Sprinkle the remaining 1/4 cup Parmesan on top. Let sit on Warm for 5–10 minutes to thicken before serving in warm bowls.
