Peel and finely dice ½ brown onion and 1 carrot. Peel and mince 2 cloves garlic. Thinly slice 2 stalks celery. In the reserved pot, heat 2 tbsp olive oil. Add the onion, carrot, garlic, celery, and 2 sprig fresh thyme. Cook for 5 minutes until the carrot is softened, stirring regularly (don’t let the onion brown). Add 4 tbsp flour and stir for 1 minute. While stirring, slowly pour in 3 cups milk. Once the flour is dissolved, add 2 cubes chicken stock, 1 cup of water and a pinch of salt, then stir.