Melt 4 tablespoons butter in a large skillet over medium heat. Add 3 sliced onions, 3 chopped anchovies and 2 teaspoons chopped thyme; season with salt and pepper and cook until the onions are golden brown, 20 minutes. Slice 1 baguette in half lengthwise. Butter the bread; top with the onions, pitted nicoise olives and a drizzle of olive oil. Bake in a 400 degrees F oven until the bread is crisp, 15 minutes. Cut into pieces; top with shaved parmesan.