If your million-dollar spaghetti casserole turned out dry, it be could a result of a few things. Overcooking the spaghetti before assembling the casserole can result in a dry texture. It's important to stop cooking them about 1-2 minutes before the completed time on the package instructions, as they will continue to cook in the oven. Also, if you didn't have enough sauce or the ratio of sauce to spaghetti was off, it could lead to dryness.