Place potatoes in a large pot and fill with water. Bring to a full boil. Cook at a gentle boil for 25 to 30 minutes, or until potatoes are very soft when poked with a fork. Strain and allow potatoes to cool.

Preheat oven to 425 degrees F.

Lightly oil a large baking sheet with cooking oil of choice. When cool enough to handle, transfer potatoes to the baking sheet. Use the bottom of a wide mug (or meat tenderizer or wine bottle) to press the potatoes until they're about 3/4-inch thick.

Drizzle potatoes generously with pesto sauce and sprinkle with sea salt. If desired, sprinkle with grated parmesan cheese.  Roast on the center rack of preheated oven 20 to 30 minutes, or until potatoes reach desired level of crisp. Serve with your favorite entree.