Preheat oven to 350℉. In a medium bowl toss together potatoes, olive oil and a sprinkle of salt and pepper.
Spread out evenly on a baking tray and bake for 30-35 minutes, turning once, until just tender.
While potatoes are baking, combine together mayonnaise, parmesan, capers, dill, lemon juice and pepper.
Remove potatoes from oven and gently flatten each with a flat surfaced utensil (I use a metal potato masher) to a third of its original height.
Set oven rack to 7" from broiler and turn oven to broil. Spread 1 tbsp of paste onto each potato. Broil for 2-3 minutes until golden and bubbly. Remove from oven and serve immediately, garnishing with fresh dill if desired.