Preheat oven to 400 degrees F. Peel the outer layers of the whole head of garlic. Making sure to leave the garlic cloves intact.
Use a sharp knife and cut the top 1/4 of the head of garlic. You want to be able to expose the garlic. Drizzle with olive oil and sprinkle with salt and pepper. Cover with aluminum foil. Bake for 40 minutes. Set aside to cool.
Once the garlic is cool enough to handle, squeeze in a large mixing bowl. Add room temperature butter, green and black olives, pimentos, mayo, cheese, and green onions. Mix well until it is all combined. *option to add jalapeño for a kick!
Preheat oven to 350 degrees F. Spread olive mixture onto French bread that has been sliced lengthwise.
Bake for 20-25 minutes or until cheese is melted and top is golden and bubbly! Slice into 1-inch pieces.