Speedy Shepherds Pie - with Cooked Lamb

I bought a ready-prepared piece of lamb in red wine sauce and roasted it - I didn't think it was that good so I minced the meat in the food processor (saving the gravy).  I also had a pack of Ready-Mashed Potatoes  ...........  Perfect! ........  made a Shepherds Pie .........

Ingredients & Method:
1. Place the minced cooked lamb into your oven-proof dish.
2. Fry over some roughly chopped Chestnut Mushrooms and a small chopped onion - fry until just softened.
3. Add the layer of mushrooms and onion on top of the meat.
Season to taste.
4. Pour some (or all) of the sauce/gravy on top of the meat - depending how wet you like the dish.
5. Break up the ready-mashed-potato and fork it on top of the meat.
If wanted, pour a little melted butter over the potatoes and bake at approx. 190 deg.C until the mixture is bubbling and the potatoes are just 'tipping' brown.

Serve with a nice green veg such as sprouts - (this may be contraversial! :) ) and Heinz Baked Beans - (excellent).

PS: Apologies - this is not my photo - we ate it too quick!