Place sweet potatoes in a steamer basket over 1 cup water in the inner pot. Close lid and set valve to sealing. Set for high pressure for 22 minutes. Do a quick release and remove the sweet potatoes from the instant pot.
Remove peelings and mash in a large bowl with a fork. Add in the sugar, butter, eggs and 1/4 c. of heavy cream and mix together until smooth. If it is too thick for you, add a bit more heavy cream.
In a separate bowl, mix together the topping ingredients.
Place 1/2 of potato mixture in a casserole dish that fits into your Instant Pot, cover with 1/2 the topping mixture, then cover dish with foil.
Add 1 cup of water to the inner pot of the Instant Pot and then lower the casserole dish into the inner pot on to a trivet. Cook on high pressure for 20 minutes.
Do a quick release when the cooking time has finished, remove from pot and serve in another dish or on a trivet (this one will be hot).