Wash peppers and remove seeds and membranes; place in an oiled slow cooker insert.
Use a large spoon or small ladle to fill each pepper about 1/3 full of chili.
Sprinkle on a covering of cheese.
Repeat twice more.
Mix the water, tomato sauce, and chili seasoning. Pour over and around the peppers.
Cover and cook on low for 4 to 5 hours, or until the peppers are to the tenderness you personally prefer.
Freezer Meal option:
Prep them just as described above and place them on a cookie sheet.
Mix the tomato sauce and chili seasoning and pour into a sandwich sized freezer bag. Label it something like "To pour around peppers, add 1/4 cup water first". You can add the water now and freeze if you like. Either works. Some people just want to conserve as much freezer space as possible.
Freeze both the peppers and the sandwich bag overnight.
After both are frozen solid remove them from the freezer and place in a large, prelabeled freezer bag or canister.
Allow to defrost overnight before cooking. OR add a 1 to 2 hour more cook time if starting with frozen peppers.