Cut the chicken breasts into 3-cm cubes and dredge with the flour. In a large frying pan, heat the oil at medium temperature and brown the chicken cubes in it, turning to brown on all sides. Add the shoestring leek pieces and sauté quickly. Reduce heat and deglaze with the maple syrup. Add the chicken broth and let simmer for about 4 minutes. Blend in the cream, add salt and pepper to taste, then bring to a boil and cook for about 1 minute.