1.Heat the oil in a large heavy-based saucepan over a medium-high heat. Add the chicken; cook until browned all over. Add the carrots, onion and garlic; cook, stirring, for about 2 minutes or until starting to soften.
2.Add the flour; cook, stirring, until the vegetables are coated.
3.Gradually stir in the stock until combined, adding just enough to cover the chicken and vegetables. Simmer, uncovered, for about 15 minutes or until chicken is cooked through, topping up stock if necessary. Season to taste with salt and freshly ground pepper.
4.Add peas; return to the boil. Add asparagus; simmer, uncovered, for another few minutes or until the asparagus is just tender.
5.Serve chicken casserole with mashed potato, if desired.