Rinse and scrub potatoes.  Place in a large pot with enough water to cover.  Bring to a boil over medium-high heat. Cook for 20 minutes or until fork tender. Preheat oven to 450° F. Line a large baking tray with parchment paper.  Place potatoes on baking sheet and smash by gently pressing down with the bottom of a glass or small saucepan.  Drizzle olive oil over smashed potatoes.  Season with salt and pepper.  Bake for 25-28 minutes or until crispy and golden brown. Transfer potatoes to a serving plate or platter.  To serve, top with a dollop of pesto and a sprinkle of lemon juice (optional).