Toss all the chopped potatoes in the slow cooker. Pour in 2 cups of chicken broth. Toss in as many whole cloves of garlic as you can handle. Add a little salt and pepper. Turn slow cooker on low, and cook for 6 to 8 hours.
Keep slow cooker on warm once the potatoes are done.
Drain excess liquid from the potatoes. Toss back in slow cooker, turn the slow cooker on low as you mix.
Break up potatoes a bit with a fork. Add butter. Use a hand mixer or ricer to mash them or leave them rustic and just use a fork or potato masher. Do not over-mix or your potatoes will become like glue. No one digs gluey mashed potatoes.
Add warm heavy cream, heat slowly on low so you don't scorch it. You just want it warm, not boiling.
Add about 1/2 cup to the potatoes to start. Mix briefly. Taste and evaluate texture. Add more heavy cream if desired. I used about 3/4 cup of heavy cream in mine, but some people like a full cup. Everyone is different so it's important to taste as you go. Always better to add slowly and taste to make sure they are perfect.
Add salt and pepper, give a quick mix and leave slow cooker on low or warm until you're ready to serve them. We leave ours in the slow cooker until dinner is ready. If you keep them on the warm setting they stay hot but don't burn. It's brilliant for keeping potatoes warm.