Preheat oven to 400°F. Place bacon on a cooling rack, placed over a large rimmed baking sheet. Monitor bacon, cooking to your desired crispness, roughly 15-20 minutes. Alternatively, bacon may be cooked in a skillet on the stovetop. Chop bacon, reserving 1 slice worth for topping later. Set aside. Chop onions and cook in bacon grease or 1Tb olive oil in a medium skillet. Cook onions until nearly translucent. Transfer to a small bowl, set aside.
Mince garlic. Chop potatoes into bite sized pieces. Add all ingredients to the bowl of a 5-6 quart slow cooker, reserving cornstarch, half and half and extra bacon bites for later. Stir to combine. Cook for 7 1/2 hours on low.
At the 7 1/2 hour mark, add half and half. Give it a quick stir, replace cover and cook for an additional 30 minutes.
Just before serving add cornstarch. Continue to add corn starch 1 tbsp at a time until you are satisfied with the consistency. If you find you have added too much, simply add a quick splash of chicken broth in and stir.
Serve warm, topped with bacon.