HEAT oven to 425°F. Cut loaf of bread into 1/2-inch thick slices. Brush 8 bread slices on both sides with olive oil, reserving remaining bread for another use. Place on baking sheet. Bake 5 minutes. Turn slices upside down.
COMBINE oregano, red pepper flakes and mozzarella cheese. Reserve 1/2 cup of cheese mixture. Divide remaining seasoned cheese evenly on top of toasted bread slices. Sprinkle each with tomatoes, olives and feta. Top with remaining seasoned cheese.
RETURN to oven. Bake 12 to 15 minutes or until cheese melts and bottoms are crisp.