Add chicken to heated oil in a pan and cook through properly.
Set chicken and veg aside until you make your cheese sauce. Preheat oven depending on pastry instructions
Add milk and half block of grated cheese to a pan. How much milk u need depends on how much sauce you need. What you see in the pan is how much sauce you will get from it.
Keep stirring cheese sauce until cheese all melted.if too runny add some corn flour and whisk until it's at a nice consistency. Add salt and pepper to taste
Take cheese sauce off heat and add your chicken and raw veg.
Add contents of pan to a heat proof oven dish
Add pastry to top of dish. You may need to cut the edges to fit dish.
Add to a preheated oven for around 35mins. The pastry packaging will let you know what temp