Cook the carrots in the microwave or in a pan of boiling water until tender. Drain and combine with the corned beef, peas, Worcestershire sauce or barbecue sauce, salt and pepper. Mix all together and put into a casserole dish.
Top it with the mashed potatoes and then sprinkle the cheese on the top of the potatoes.
Bake in a preheated 180 C / Gas 4 oven for about 20 minutes until browned.
If you prefer you can put baked beans into the cornbeef or any other vegetables you desire.