Saute the diced onion in the bacon grease until tender. Drain and set aside.
Chop the potatoes into small chunks.
Add the potatoes, chicken broth, onions, salt, and pepper to a large stock pot.
Bring the potatoes to a gentle boil, allow to cook until just tender, about 10-15 minutes. You want them soft, but not falling apart.
In a small bowl, whisk together the milk and flour.
Scoop out 1/2 to 2/3 of the potatoes and broth mixture into your blender. Blend using the soup button, or about 30-60 seconds until desired consistency.
Add the flour and milk mixture to the remaining potatoes on the stove.
Gently pour the blended potatoes back into the stock pot.
Remove from heat and fold in the cream.
Add remaining chopped bacon and other fixings such as shredded cheese and green onions.