Heat oven to 400°. Melt butter in a large skillet over medium heat. Add onion and garlic; season with salt and pepper. Cook until onions are soft. Add sundried tomatoes and cook for 1 minute. Transfer to large bowl. Stir in bread, egg, cheese, pine nuts, and parsley. Season with salt and pepper. Add broth, ½ cup at a time, until mixture is moistened but not wet. Transfer mixture to a buttered baking dish and drizzle with olive oil. Cover with foil and bake for 30 minutes. Uncover and bake until golden and crispy, about 20 minutes.