Scrub (but don't peel) potatoes and cut into large cubes then place all the pieces in a large plastic bag. Add about 3/4 cup pesto sauce to the bag and shake it around until the pesto is coating all the potato pieces.
Pour the contents of the bag out onto a cookie sheet. Arrange the potatoes so they are laying flat then sprinkle with parmesan cheese.
Bake at 450 degrees for 25 to 30 minutes, or until they begin to look lightly toasted.