Place potatoes in a steamer basket over 1 cup water in the inner pot of your Instant Pot. Secure lid and set valve to sealing. Press "Manual" and set time for 22 minutes. When the cook time has finished, move the valve to venting to quick release the pressure. After the pressure has fully released remove the sweet potatoes from the Instant Pot.
Carefully remove peelings and mash in a large bowl with a potato masher (if you don't have one, you can use a fork). Add in the sugar, butter, eggs and heavy cream and mix together until smooth.
In a separate bowl, mix together the topping ingredients.
Place potatoes in a casserole dish or pan that fits into the Instant Pot (it is okay to divide between two pans) and then cover with the topping.
Add 1 cup of water to the inner pot of the Instant Pot and then lower the casserole dish into the inner pot on a trivet. Cook on high pressure for 20 minutes and allow for a quick release of pressure when the cooking time has finished.