First roast the garlic by wrapping either the six cloves or a whole head in foil. Roast in a pre heated oven 200 for 25 minutes. Set aside.
Next wash the lentils and pick through and remove any little stones found. Put the lenils, 6 garlic cloves still in their papery skin, diced carrot, paprika, chestnuts, the chicken stock and a good grinding of pepper into a large pot. Bring to the boil then turn down to a simmer for 45 minutes. Check occasionally and add a little boiling water if it needs it. Then add the celeriac and continue cooking for another 10-15 minutes or unil they are tender. Fish out the garlic and squeeze the pulp from the skins back into the lentil soup. Taste for seasoning and add salt – it will need quite a bit. Slosh in about 3 tablespoons of olive oil and stir in the parsley. Ladle into bowls and drizzle over more olive oil. Serve with sour dough bread.