Chicken Strips in Leek Sauce

Name: Chicken Strips in Leek Sauce
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Yield: 3
Ingredients: 300 g chicken breast; 1 large or 2 small leeks; 2 cloves garlic; 1 tbsp plain flour; 1 tsp mustard; 1 cup milk + extra as needed; oil; butter; salt; pepper; a small pinch of mace; cream for finishing (optional); water as needed