While the crockpot is heating, brown the Italian sausage in a skillet over medium-high heat, breaking it into small pieces as it cooks, about 5-7 minutes until no pink remains. Drain excess fat if needed. While the sausage cooks, combine the softened cream cheese, sour cream, Italian seasoning, and garlic powder in a bowl, mixing until smooth and well combined. I like to use room-temperature cream cheese because it blends much more easily without lumps, creating a silkier texture throughout the dish.

Pour half of the marinara sauce (24 oz) and 1/2 cup water into the crockpot, stirring to combine. Break half of the spaghetti in half to fit the pot size and layer it evenly over the sauce mixture, breaking any large clumps. Spread the cooked sausage evenly over the noodles, then spoon the cream cheese mixture from Step 1 over the sausage layer, spreading it to cover as much surface area as possible.

Add the remaining broken spaghetti as the final noodle layer over the cream cheese mixture. Pour the remaining marinara sauce (24 oz) and 1 cup water over the top, stirring gently to distribute the sauce throughout without completely mixing the layers—this helps ensure even cooking and flavor distribution.

Cover the crockpot and cook on LOW for 2.5 hours. The noodles should be tender and the sauce should be bubbling gently around the edges. I find that cooking on low heat rather than high ensures the cream cheese mixture stays creamy instead of breaking and becoming grainy.

After 2.5 hours, stir the pasta gently to combine all the layers. Sprinkle the mozzarella cheese evenly over the top, cover, and cook on LOW for another 30 minutes until the cheese is melted and bubbly.

Turn off the crockpot and let the dish rest for 5 minutes before serving. This allows the cheese to set slightly for better scooping and serving. Top each portion generously with fresh parsley.