Soak the cowpeas in enough water for about 30 minutes to 1 hour.
After soaking, discard the water used for soaking and rinse the cowpeas in fresh water and transfer it to a large sized pressure cooker.
Add the diced butternut squash and greens also to the pressure cooker.
Add the water and also enough salt.
Also add all the spices to the cooker - garlic powder, onion powder, turmeric powder, red chili powder, garam masala powder, coriander powder and cumin seeds powder. Mix everything well.
Close the pressure cooker following the instructions in the manual and cook in medium heat for about 10 minutes after the steam comes or until 3 to 4 whistles.
After the cooking is done, switch off the stove and wait for the pressure cooker to cool down.
Once the cooker is cooled enough, open the cooker and see if the red cowpeas is cooked and soft.
Stir everything well, and if you need more gravy, you may add a little more water and simmer the contents for another 1 to 2 minutes.
To prepare the seasoning, heat the oil in a different pan and add the cumin seeds. When the cumin seeds are lightly fried, add the minced onions too and fry until the onions are lightly brown (the minced onions brown so quickly so make sure to watch or it can burn). If using mustard seeds instead of cumin seeds, you need to wait until the mustard seeds are spluttered to add the minced onions.
Pour the prepared seasoning over the curry in pressure cooker, gently mix in.
Finally add the heavy cream and stir well with the curry. Delicious butternut squash curry is ready to be served with rice!