Heat a cast iron skillet on medium heat. Add the bacon or pancetta and cook until browned. Remove the bacon, leaving the grease in the pan and drain on a paper towel. Add the sliced, cleaned leeks (make sure they are dry) to the bacon grease and saute until caramelized, about 6-8 minutes. At this point you can add more butter/olive oil if needed – I added a tiny bit of bacon grease I had stored in the fridge.

Add beans and bacon back into the skillet. Stir for about a minute. At this point you can either fry some eggs in a separate skillet, or push the hash to the sides and fry the eggs in the middle. Make sure the beans, leeks and bacon are thoroughly mixed.

Serve the hash with the eggs on top.