Place tomatoes, ginger, garlic, turmeric, cayenne, smoked paprika, salt, and garam msala into a blender in the order listed. Blend until smooth.
Add the blended sauce to the slow cooker. Place the chicken on top of the sauce.
Place the lid on the slow cooker and allow everything to cook for 4-5 hours on high or 8 hours on low.
Open up the slow cooker, remove the chicken carefully and set aside.
Add the cut up butter and cream and stir until well incorporated.It's best to let the sauce cool just a little before adding the butter and the cream. Adding it into the boiling sauce will make your sauce very thin. If that happens, just put it in the fridge for a little and let it thicken up. It should be thick enough to coat the back of a spoon
Take out half the sauce and freeze for later or store in the fridge for 2-3 days
Add the chicken back in and heat through. Add the remaining cilantro and garam masala and mix. Break it up into smaller pieces if you need but don't shred it.
Serve over rice or zucchini noodles
Using leftover sauce
Use leftover cooked chicken and mix in with the gently heated sauce, let it simmer for a few for the flavors to meld together and there you go. Add some fresh cilantro on top.
You could also use this for Paneer Makhani. Defrost a cup of peas and 1 cup of paneer and mix gently into the heated sauce and let it simmer for a few for the flavors to meld together and there you go.
If you use a stand blender, be very careful with the hot sauce and be sure to leave the inside lid open to vent.
For this recipe, the garam masala is very, very, important. Unlike other recipes, I didn't use whole spices because I've learned that not everyone has whole cinnamon sticks, whole cloves, and green cardamom lying around. So we'll use garam masala instead and I must urge you to make this homemade garam masala recipe! It makes a HUGE difference.
Let the sauce cool just a little before adding the butter and the cream. Adding it to the boiling sauce will make your sauce very thin. If that happens, just put it in the fridge for a little and let it thicken up. It should be thick enough to coat the back of a spoon.