Preheat oven to 400 degrees F. Place grapes in an ungreased shallow baking pan. Roast, uncovered, 20 to 25 minutes or until browned and starting to burst; set aside.
In a large bowl combine the flour, sugar, baking powder, and salt. Using a pastry blender, cut in butter until mixture resembles coarse crumbs. Make a well in center of flour mixture; set aside.
In a medium bowl combine egg, creme fraiche, and 1/4 cup whipping cream. Add egg mixture all at once to flour mixture. Add roasted grapes and rosemary. Using a fork, stir just until moistened.
Turn dough out onto a lightly floured surface. Knead dough by folding and gently pressing it for 10 to 12 strokes or until dough is nearly smooth. Pat dough into a 10x4-inch rectangle. Cut in half lengthwise and in sixths crosswise to make 12 rectangles.
Place rectangles 2 inches apart on an ungreased baking sheet. Brush rectangles with additional whipping cream. Bake 13 to 15 minutes or until golden brown. Remove scones from baking sheet. Serve warm.