1. Preheat oven to 400F. Wash and scrub potatoes and place on baking sheet.
2. Bake in oven for about 1 hour or slightly longer as needed, until potatoes are soft (they should have some give when you touch them).
3. While potatoes are cooking, make the cauliflower mash. Cook cauliflower florets in boiling water until very soft.
4. Drain from water and place into food processor. Make sure to eliminate as much of the water as possible so your mash isn't watery. Process cauliflower until completely mashed.
5. Add in sour cream and Parmesan cheese. Process until mash is creamy and smooth.
6. Add in 1/2 cup cheddar cheese and half of the bacon bits and pulse a few times to mix into the mash.
7. When potatoes are done, slice them in half, lengthwise. Using a sharp spoon, scoop out most of the potato flesh, leaving a small amountaround the edges (about 1/4 inch) to hold the shell together. The leftover potatoes can be used to make traditional mashed potatoes. Pile empty potato shells high with the cauliflower mash. Sprinkle remaining cheese and bacon bits on top of each potato.
8. Place potatoes back into oven and bake about 10 minutes, or until cheese is melty and potatoes and mash are warm.
9. Garnishpotatoes with chopped scallions before serving.