Cut the potatoes into chunks and place them in inner pot of your Instant Pot.
Pour chicken stock, salt and garlic powder.
Place a rack over the potatoes and put the turkey breast.
Wrap sweet potatoes in a foil and place them next to turkey.
Cover the lid and make sure the valve is set to “sealing”.
TO PRESSURE COOK, set the Instant Pot to Manual/Pressure Cook for 30 minutes (or 10 minutes per lb) on High. (NOTE: It took about 25min for my IP to come to pressure.)
Once the time is up, allow the pressure to release naturally for at least 20 minutes, and then carefully turn the valve to venting. Once the pin drops, carefully open the lid.
Remove sweet potatoes, using a pair of kitchen tongs.
Check the internal temperature of the turkey breast and make sure it reached at least 165°F.
To broil the turkey, using a pair of kitchen tongs, transfer the turkey breast onto a baking sheet and broil for 3-5 minutes at 500°F to brown the meat. Keep a close eye on it to prevent burning!
To make the mashed potatoes, add milk and butter into the potatoes. (No need to drain the liquid.) Using a potato masher, mash the potatoes into a smooth texture. Transfer onto a serving platter and keep warm.
Clean the inner pot.
To make the gravy, hit "cancel" button and set the Instant Pot to Sauté.
When the display reads “HOT”, add butter (or bacon fat) and melt it. Once the butter is fully melted add flour and roast the flour, whisking constantly, until golden brown with nutty aroma, about 2 minutes.
Slowly pour in chicken stock, while whisking constantly. Once all the stock is added, bring it to a boil, whisking occasionally. Then turn off the Instant Pot and let the gravy simmer for another 5 minute or so.
To serve, slice the turkey breast and arrange on a serving platter. Unwrap and cut sweet potatoes in half, serve with ½ tablespoon of butter.