In food processor, pulse 0.75 of the flour, the yeast, sugar and salt with metal blade until blended, about 2 pulses. Add water, egg and butter and process until blended, about 30 seconds. Add remaining flour, quarter cup at a time, pulsing twice after each addition. Process for 45 seconds after dough begins to clean side of bowl. Place dough in a large floured plastic food storage bag. Twist to squeeze out air and seal at top with a twist tie. Let rise until doubled, about 55 minutes. Drain olives and pat dry on paper towels. Pulse-chop coarsely, 3-4 times, reserve. Punch down dough and turn onto floured work surface. Pat or roll form into 14 x 36 cm square. Let rest 3-4 minutes. Spread chopped olives evenly over dough to within 3 cm of the edge and press lightly. Roll up jelly-roll style. Tuck ends under and pinch together ends and seams. Place seam side own on greased baking sheet sprinkled with cornmeal. Cover with oiled plastic wrap and let rise 25 minutes. Preheat oven to 180ºC . Brush loaf with egg yolk, bake until brown 40-45 minutes. Cool on wire rack. Serve warm.