Place the potato chunks in the Ninja Foodi's inner pot.
Add water to cover the potatoes and season with salt.
Close the Ninja Foodi lid and select the "Pressure" cooking mode. Set the timer for 10-12 minutes (adjust based on the size of your potato chunks).
Ensure the pressure release valve is in the sealed position.
Once the pressure cooking cycle is complete, use the quick-release method to release the pressure.
Open the lid and drain the potatoes.
Return the drained potatoes to the inner pot.
Add butter and milk to the potatoes.
Use a potato masher, hand mixer, or potato ricer to mash the potatoes while gradually mixing in the butter and milk.
Continue mashing until you achieve your desired creamy consistency.
Customize your mashed potatoes with optional add-ins like minced garlic, fresh herbs, grated cheese, or sour cream.
Taste and adjust the seasoning with salt and pepper if needed.
Serve the creamy Ninja Foodi Mashed Potatoes hot.