In a large mixing bowl, toss the potatoes with 1/2 cup of olive oil, rosemary, and a generous seasoning of salt and pepper. Coat a small roasting pan with the remaining olive oil and put the potatoes in the pan, cut-side down. Bake for 50 to 60 minutes, until the potatoes are tender on the inside and golden on the outside.
Let the potatoes cool slightly and then arrange on a serving platter. Serve the potatoes with the creme fraiche, caviar, and chives for self-service hors d'oeurves. This goes great with champagne. If you wish, spread each potato with a 1/4 teaspoon of creme fraiche and 1/2 teaspoon caviar instead of dipping.