Creamy Tomato and Curry Lamb

Might you have wondered what I did with the left over leg of lamb from that Lamb Shawarma from the other night?  After all, though we obviously love to eat, that was a lot of lamb.  Having left overs is a common occurrence in our house given that we love to roast large pieces of meat.  I often make them into pasta dishes, sometimes use them in sandwiches, and tonight I'm taking the lamb and making a variation of my kids' favorite Indian dish, butter chicken.  Here's a nice helping of butter lamb.  

1 to 1.5 pounds cooked leg of lamb, cut into 1-2" pieces
3 tablespoons butter
1/2 large sweet onion, finely chopped
3 cloves garlic, finely chopped
1 tablespoon garam masala
1 teaspoon ground ginger
1/2 teaspoon cinnamon
up to 1 teaspoon cayenne pepper (I used none because of my kids)
1 tablespoon tomato paste
1 cup finely diced tomatoes
15 oz can tomato sauce
1/3 cup heavy whipping cream

In a large pot, heat butter over medium heat.  Sauté the onions until light golden brown.  
Add the garlic, garam masala, ground ginger, cinnamon, cayenne (if using) and tomato paste. Stir to combine and sauté until fragrant.
Add the tomatoes and tomato sauce and bring to a boil.  Let boil gently for a couple of minutes.
Add the lamb and bring back to a boil.  Turn heat down, cover and simmer for about 10 minutes
Add cream and bring back to a boil.  Boil uncovered until sauce is slightly thickened.
Serve with rice and good naan if you can find it.

This is a keeper.  There was no way to photograph this and make it look pretty.  But as Chris said, we should have this every time we have left over lamb.  It was really good.