I keep it very simple. When I make my gravy from the pot roast drippings I put 1/2 of it back to use in my pie. I chop up leftover roast and veggies and also use any veggies I have hanging out my fridge that are left over. I mix them together with the gravy. I take mashed potatoes (normally I make extra earlier in the week and put them in fridge) and mix in a little garlic powder. I spray a baking dish and put in the roast/veggie/gravy mix and spread the potatoes over the top. I brush the top of the potatoes with olive oil and then dot with a few pea size pieces of butter. Into the oven at 350 for 40-50 minutes and that is it. I also sometimes make it in the morning and stick it in the fridge. When DH get's home he sticks it in the over and dinner is ready in a short time.
Thank you!