To prepare the aloo palak biryani, start by cooking the rice and potatoes. In a pressure cooker or instant pot with separators place the washed rice with 2 cups water and pinch of salt in one compartment. Place the quartered potatoes in another compartment. Pressure cook for one whistle, keep on sim for 3-5 minutes and switch off the flame. The rice and potatoes need to be just cooked and not mashed.
While the pressure cooker is doing its work, prepare the aloo palak masala to go with the rice. In a large kadai, heat ghee. Add all the whole spices. Stir for a few seconds, then add the sliced onions, ginger-garlic paste. Saute on medium heat for 6-7 minutes, until onions are translucent.
Add the shredded spinach and fry on high heat until it is wilted. This will take around 2 minutes.
Once the cooker is cool enough to be opened, remove the potato cubes. Remove the rice onto a large dish, gently separate with fork and allow to cool for 10-15 minutes.
Add the potato cubes to the onion-spinach mix along with the spice powders, yogurt and salt. Toss gently to coat the potato with spices, let this cook on low heat for 7-8 minutes with occasional turning, so that the onion-spinach-spice mix coats the potatoes.
Add the crumbled paneer towards the end (if using) and toss gently.
Add the cooked rice to the mix in the pan along with the saffron milk, toss gently till evenly mixed. Cover this with a tight light and let the flavours come together on low heat for 5 more minutes.
Serve hot paired with a raita.