Cook the bacon in a deep pan over moderate heat until the fat renders.
Add two chopped onions and carrot chunks to the pan.
Cover and steam the vegetables for a few minutes.
Stir in the paprika, cinnamon, and a half-grating of nutmeg.
Add lentils, stock, and 500ml of water.
Cover and simmer for 30 minutes until the lentils are soft.
Slowly cook the remaining two sliced onions in butter until golden brown.
Season the caramelized onions with a final grate of nutmeg.
Stir chopped parsley into the finished lentils.
Serve the stew with a dollop of crème fraîche and the caramelized onions on top.