Boil the chicken stock in a large saucepan for 10 minutes, or until it has reduced to 2 cups of liquid.
Meanwhile, cook the pasta in a large saucepan of rapidly boiling water until al dente.
Drain and toss with 2 tablespoons of olive oil.
Heat the remaining oil in a large deep frying pan, add the carrot, onion and celery and cook over medium heat for 10 minutes, or until lightly browned.
Add two thirds of the crushed garlic and the thyme and cook for a further minute.
Add the stock, and bring to boil and cook gently for 8 minutes, or until reduced slightly and the vegetables are tender.
Gently add the lentils and stir until heated through.
Stir in the remaining garlic and a little extra thyme, and season with plenty of cracked black pepper and sea salt.
The stock should be slightly syrupy at this point.
Combine the pasta with the lentil sauce in a large bowl, drizzle generously with olive oil and serve with grated parmesan if liked.