Peel potatoes and cut into 1 in cubes. Pressure cook in Instapot for 4 minutes with quick release of pressure

Add butter, cheese, milk and 1/4 salt to sauce pan. Heat on medium until mixture is smooth.

Combine potatoes and cheese mixture.

Fold in egg.

Place in small, greased baking dish. Bake on 350, uncovered, for 40 minutes or until fluffy and golden brown.