Use a 6-quart slow cooker sprayed well with cooking spray. Put the wet pasta into the insert and add the diced pepperoni. Add sliced mushrooms and stir in the pasta sauce, retaining the jar. Stir in shredded cheese. Put the warm water into the empty sauce jar and seal. Shake well and pour the liquid evenly over the top.

Cover and cook on low for 6-8 hours, or on high for about 4 hours. To ensure that all the moisture stays in the pot to fully cook the pasta, be sure that the lid of the slow cooker fits nicely and condensation beads up while it’s in use. If you do not see that happening, simply put a piece of foil over the top, crimp the sides, then replace the lid.