Combine Pasta and Sauce: Pour the dry, uncooked pasta into the slow cooker. Add the jar of marinara sauce.
Add Water: Fill the empty marinara jar with water (about 2 to 3 cups) and pour it into the slow cooker. This extra liquid is essential—it’s what the dry pasta will “drink” to cook through.
Layer the Cheeses: As seen in your photo, dollop the ricotta cheese over the top of the pasta. You can leave it in patches for “cheese pockets” or spread it slightly. Top the entire dish with the shredded mozzarella.
Slow Cook: Cover and cook on Low for 2.5 to 3 hours.
Note: Start checking at the 2-hour mark. All slow cookers heat differently, and you want the pasta tender but not mushy.
Serve: Once the pasta is al dente and the cheese is bubbly and melted, give it a very gentle stir if you want the ricotta incorporated, or scoop it as-is to keep the layers distinct.
A Few Pro-Tips
The “Lid Trick”: If you notice a lot of condensation on the lid, place a paper towel under the lid (stretched across the top of the pot) for the last 30 minutes. This prevents the cheese from getting “steamed” and keeps it gooey.
Boost the Flavor: Since this is a 4-ingredient recipe, the quality of your marinara matters! Pick a brand with garlic or basil already included for extra punch.
Checking for Doneeness: If the pasta still feels a bit firm after 2 hours but the liquid is gone, splash in another 1/2 cup of water and keep cooking for 20 more minutes.