Turn on Saute mode in Instant Pot or any electric pressure cooker. When the display reads 'hot', add 1 tablespoon oil.
Sprinkle a little garam masala and salt on chicken breast (or thighs) and place it seasoned side down in the cooking pot. Let it brown for 1 minute. After that, flip the chicken and season the other side with a pinch of garam masala and salt and cook for 1 minute. Remove chicken and keep aside.
Add the remaining 1 tablespoon oil and cumin seeds. As soon as the sizzle (takes about 30 seconds), add sliced onions, halved green chili/pepper and crushed ginger and garlic. Saute for 1 minute.
Add all the spices along with ½ cup water. Turn off Saute mode. Use the water to deglaze the pot, which means scrap any brown bits in the cooking pot.
Add baby spinach leaves and toss them well. Place the chicken on top of the spinach. Close the lid. Set 8 minutes on Pressure cook or manual mode. If using chicken thighs, adjust time to 6 mins.
When cooking time is up, manually release the pressure. When the pin drops, open the lid.
Remove the chicken and keep aside. Using an immersion blender, blend the spinach into a smooth consistency. Cut the chicken into bite size pieces and add it back to the spinach curry.
Optional step: Stir in 1 teaspoon of butter. This gives the curry a gorgeous shine.
Seasoning the chicken adds another level of flavor to this curry, so avoid skipping that step.
If you don't have the time to briefly brown the chicken, simply season it with garam masala and salt before placing it on top of the spinach.
If making this curry with boneless skinless chicken thighs instead, reduce the pressure cooking time to 6 minutes,
You can also make this curry with mixed greens, like spinach, mustard, kale, etc. As long you match the quantity of the greens to around 10-12 ounces, you can make this recipe with any greens of your choice.
When making this curry ahead of time for entertaining, break it up into two steps. Prepare the chicken curry (without spinach) a day earlier. On the day of, microwave the greens, puree them, and simmer with the chicken curry before serving.
To make Restaurant-style 'extra creamy' Chicken Saag, you can add ¼ cup heavy whipping cream or cashew cream towards the end along with chicken pieces and simmer.
Note: The nutrition facts below are my estimates. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.