While the chicken is cooking you can start on your curry.
Cut your onion into a small dice and roughly chop the cilantro into pieces. Mince up the garlic and ginger. If you're using fresh cauliflower and butternut squash, cut them into a medium to large dice.
In a large skillet over medium high heat and add in about 1 tsp of oil and toss in the cauliflower and squash. You can put the vegetables straight into the pan from frozen. Season lightly with salt and allow them to cook for 3-5 minutes.
Create some space in the center of your pan and add another 1 tsp of oil and add the onions. Cook until the onions start to develop some color.
Create some more space in the center of the pan and add the last remaining 1 tsp of oil. Add in the garlic, ginger, chili powder, cumin, and garam masala. Allow the spices to bloom for about 20-30 seconds and then mix everything together.
Reduce the heat to medium low and add the canned tomatoes and water. Stir to combine and allow the tomatoes to cook down a bit and stew for 8-10 minutes.
Move the contents of the skillet into a blender and blend until smooth. Alternatively if you have an immersion blender you can do this right in the pan. Note that if your blender isn’t the greatest, you’ll likely have trouble getting a smooth texture. Adding a bit more water can help but then you’ll need to boil it off later.
Return the blended sauce to the pan over low heat. Add in the peanut butter, Greek yogurt, turmeric, butter and season with salt and pepper to taste. Note that the reason I wait to add the turmeric until now is because it will stain your blender. If you are using an immersion blender you can add it with the other spices.
Stir in the yogurt, butter, and peanut butter until they are incorporated then dump in the diced chicken thighs and stir to cover.