Slice the potatoes in a food processor. 

Select Saute and add butter to the pressure cooker pot. When butter is melted, add the onion and cook, stirring occasionally until the onion is tender, about 5 minutes. Add 1 cup chicken broth, salt and pepper to the onions.

Put the steamer basket in the pressure cooker pot. Add the sliced potatoes. Lock lid in place, select High Pressure and 2 minutes cook time and start.

Optional
Preheat broiler. In a small bowl, mix the panko with 3 tablespoons melted butter. Set topping aside

When timer beeps, turn off pressure cooker and do a quick pressure release. Carefully remove potatoes and steamer basket from the pressure cooking pot. Place potatoes in a greased 9×13 oven safe dish.

Stir sour cream and cheese into cooking liquid in pressure cooker. Pour over potatoes. Use two forks to gently mix sauce with the potatoes. Top with panko topping and broil for 5- 7 minutes or until golden brown.