Chicken Makhani (Indian Chicken)

I know it's January lighten up time, and this reads like a fatties entree, I have attempted to lighten it.  You can either serve it over rice or with a side of Naan bread.  I am also very nervous to post this.  I have an friend that is Indian and cooks the most amazing food.  Don't be too hard on me Palak!  To make this dish you will need:  
Spice Blend: 
1 tablespoon garam masala seasoning
1 1/2 teaspoons ground ginger
1/2 teaspoon ground cinnamon
1/4 teaspoon cayenne 
Sauce:
3 tablespoons butter
1 pound of chicken breasts, cut in bite sized cubes
1 large onion, chopped (about 1 cup)
2 teaspoons jarred minced garlic
1 tablespoon tomato paste
1 (15-ounce) can tomato sauce
1 (14 1/2-ounce) can diced tomatoes in juice
1 cup frozen peas, defrosted
1/3 cup fat free half and half
Optional:  Hot basmati rice, for serving or Naan bread warmed
1.)  To make the spice blend: Stir the ingredients together in a small bowl and set aside.
2.)  Melt the butter in a large nonstick skillet over medium heat. Add the onion and chicken,cooking stirring frequently, until the pieces just begin to turn gold and the onion is soft, about 5 minutes. Add spice blend, and cook for 1 minute, stirring constantly to prevent burning. The spices will be fragrant. Add the the garlic, tomato paste, tomato sauce and diced tomatoes and stir will.  Bring to a simmer. Turn the heat to low and cook, uncovered, until the chicken is cooked through and the sauce is flavorful, about 10 minutes. Stir frequently.
3.)  Add the peas and the half and half and heat through.  Serve either over cooked basmati rice or with Naan bread for dipping into the awesome sauce!