Step 2: Add the Pasta
Scatter the uncooked pasta evenly over the vegetable layer. Do not stir—this helps the pasta cook evenly without becoming mushy.
Step 3: Mix and Pour the Sauce
In a medium bowl, whisk together the vegetable or chicken broth, heavy cream (or half-and-half), and ¾ cup of the grated Parmesan cheese until combined. Carefully pour the liquid mixture over the pasta, ensuring most of the pasta is submerged. Gently press down any pieces sticking above the liquid to encourage even cooking.
Step 4: Cook Slowly
Cover the slow cooker with the lid and cook on Low for 2–3 hours. Check around the 2-hour mark and stir gently halfway through cooking for even texture. The dish is ready when the pasta is tender and has absorbed most of the liquid.
Step 5: Stir in Spinach
Add the fresh baby spinach to the slow cooker and gently fold it into the pasta. The residual heat will wilt the spinach within about a minute. If the sauce has thickened too much for your liking, add a small splash of extra broth and stir to loosen it.
