I loooooove tikka masala.  I want to try other things when I go to Indian restaurants, but it's hard because I love it so much.  The most I really branch out is that sometimes I get paneer masala instead of chicken.  My two favorite Indian restaurants in the Seattle area are 
Chutneys and 
India Gate, in case you're looking for a recommendation. (Kelly--this is specifically for you.)   
My favorite thing about Indian food is dipping naan in the sauce.  But, naan is tricky if you don't have a tandori oven, which I don't.  Luckily my sister-in-law, Britney, discovered a recipe for 
green pea bread years ago which is the perfect substitution for naan.  Totally different than naan, but totally perfect for dipping in delicious sauce.  Man, I love green pea bread.  So simple, so delicous. I love it.  Recipe to follow very soon.    
  
On to the tikka masala . . .  This recipe was such a pleasant surprise.  This is by far my favorite tikka masala that I've made.  The key ingredient is garam masala.  Garam masala is a blend of spices and includes things like coriander, cumin, pepper, nutmeg, fennel.  This recipes calls for a lot, 3 tablespoons, so head on down to the 
Market Spice to buy an ounce or two.  This is the only way to buy spices.
I really love this recipe.  Enjoy!
 
CHICKEN TIKKA MASALA
- 3-4 chicken breasts
- Kosher salt
- ground coriander
- cumin
- 1/2 cup plain yogurt
- 2 tablespoons butter
- 1 large onion, diced 
- 4 cloves garlic, minced or pressed 
- 1 piece (approximately 2 inches) fresh ginger, peeled and grated 
- 1 tablespoon salt
- 3 tablespoons garam masala
- 1 can (28 ounce) diced tomatoes
- 1 tablespoon sugar
- 1 1/2 cups heavy cream
- cilantro
- 1/4 teaspoon cayenne pepper 
Season chicken breasts with Kosher salt, coriander, and cumin on both sides. 
Coat chicken breasts completely with plain yogurt and set on a metal cooling rack over a foil lined baking sheet.  
Place about 10-12 inches below a broiler for 5-7 minutes per side. Watch carefully so as not to totally char the chicken. It should have slightly blackened edges. Remove from oven.
In a large skillet, melt 2 tablespoons butter over medium high heat. 
Add the onions and sauté until they are slightly browned. 
Add garlic, ginger, and 1 tablespoon of salt and cook for a few more minutes.  
Add 3 tablespoons garam masala and stir well.  
Add tomatoes (inlcuding the juices).
NOTE:  I used two 14 ounce cans of tomatoes.  I think I would puree one of the cans next time so that it's a little more saucy.  I'd like it to be both saucy and chunky, if that's a possibility.  
Continue cooking and stirring, scraping the bottom of the pan to deglaze it. 
Add 1 tablespoon sugar to cut the acidity.
Add cayenne pepper if you want a little kick.  I'm a spice wimp and 1/4 teaspoon was perfect for me.  Adjust accordingly.  
Simmer on medium for about 5 minutes.
Add in 1 ½ cups of heavy cream. 
Chop up your chicken breasts into chunks and stir them into the sauce. 
Add a handful of chopped fresh cilantro and stir well. 
Serve with 
green pea bread or naan.  Mmmmmmmm.  
I made this 
turmeric rice as well, but like it just as much with just plain old rice.  
Source:  Pioneer Woman