Food & Cooking Recipes Dessert & Treats Recipes Pie & Tarts Recipes Caramelized Onion Tart with Olives 3.7 (68) 3 Reviews By Martha Stewart Editors Martha Stewart Editors Facebook Instagram Twitter Website An article attributed to "Martha Stewart Editors" indicates when several writers and editors have contributed to an article over the years. These collaborations allow us to provide you with the most accurate, up-to-date, and comprehensive information available.The Martha Stewart team aims to teach and inspire readers daily with tested-until-perfected recipes, creative DIY projects, and elevated home and entertaining ideas. They are experts in their fields who research, create, and test the best ways to help readers design the life they want. The joy is in the doing. Editorial Guidelines Updated on June 12, 2017 Print Share Share Tweet Pin Email Prep Time: 20 mins Total Time: 1 hrs Servings: 4 Anchovies are the surprise ingredient, adding another layer of umami to this savory tart. Ingredients 1 tablespoon unsalted butter 2 tablespoons extra-virgin olive oil 2 medium onions, thinly sliced 2 tablespoons fresh thyme, leaves All-purpose flour, for dusting 1 sheet frozen puff pastry, thawed ¼ cup oil-cured small black olives, pitted and halved lengthwise 4 to 6 anchovy fillets (optional), rinsed Directions Preheat oven to 425 degrees. Melt butter with oil in a skillet over medium-high heat. Add onions and thyme, and cook until onions are golden and soft, about 10 minutes. On a lightly floured surface, roll out pastry, and trim to an 8 1/2-by-15-inch rectangle. Place on a parchment-lined baking sheet, transfer to oven, and immediately reduce oven to 400. Bake until pastry begins to rise, about 12 minutes. Arrange onions in a single layer over pastry, leaving a 1-inch border around edge. Top with olives and anchovies if using. Bake for 15 minutes. Reduce oven to 375 degrees, and bake until puffed and golden brown, about 15 minutes more (tent with foil if crust browns too quickly). Cut into squares. Print