The bacon for this colorful tart gets baked with a little brown sugar on top, which gives it a shiny, candied glaze. For the prettiest tart, try to find a mix of different colored heirloom tomatoes, though a tart made all red tomatoes will be just as delicious. Pre-made puff pastry makes this recipe a breeze to put together.
Technique tip: Draining the tomatoes while the bacon cooks helps keep the tart's crust nice and crunchy.
Swap option: For a vegetarian version, leave out the bacon and crumble 4 tablespoons of blue cheese over the tomatoes before baking the tart.
Heat the oven to 375 F and line a rimmed baking sheet pan with parchment paper or foil.2.
Arrange the bacon on the prepared pan, then sprinkle with the brown sugar and grind on some black pepper. Bake until crisp and golden, about 20 to 25 minutes.3.
Meanwhile, spread the tomato slices on a clean kitchen towel, or a double layer of paper towels, and sprinkle liberally with salt and pepper. Let the tomatoes drain while the bacon cooks.4.
When the bacon is cooked, transfer the pieces to a paper towel-lined plate to cool. Crumble the bacon. Raise the oven temperature to 400 F.5.
Line another rimmed baking sheet with a piece of parchment paper. On top of it, roll out the puff pastry into a 9- by 11-inch rectangle. Prick all over with a fork every few inches, leaving a 1/2-inch border. Using a pastry brush, coat the center of the puff pastry with the mascarpone or crème fraîche, leaving the border unbrushed. Sprinkle with the Parmesan cheese.6.
Staying within the border, layer the tomatoes on top of the tart, allowing them to overlap slightly. Add the crumbled bacon on top and sprinkle with more Parmesan. Bake, rotating halfway through, until puff pastry is browned and puffed, 30 to 35 minutes.7.
Transfer tart to a wire rack and let it cool for at least 10 minutes before serving. When you're ready to serve and plate, scatter lettuce and herbs on top of the tart, drizzle with olive oil, then sprinkle with flaky salt. Serve hot or at room temperature.