Tantalizing White Onion & Tuna Tart

1. Slice the tuna into ½-inch thick slices if not pre-sliced. | 2. Season liberally with salt and freshly ground black pepper. Set aside.

1. Melt butter in a Dutch oven over medium heat. | 2. Add the sliced onions and sauté until translucent, being careful not to brown them. | 3. Reduce heat to very low, cover the Dutch oven, and cook for about 20 minutes, stirring occasionally to prevent browning. Onions should become soft, lightly yellow, and most juices should evaporate. If not, continue cooking in 5-minute increments.

1. In a bowl, whisk together the eggs and cream. | 2. Remove the onions from heat, then mix in the egg and cream mixture thoroughly until smooth and creamy. | 3. Season with salt, pepper, and a touch of nutmeg. | 4. Gently fold in the grated cheese and stir to distribute evenly. Add a sprinkle of paprika if desired.

1. Lightly flour your work surface and roll out the puff pastry to be slightly larger than your baking dish (e.g., a 10-inch pie pan). | 2. Line the baking dish with the puff pastry, pressing it into the edges to form a pie shell. | 3. Prick the bottom of the crust all over with a fork to prevent bubbling.

1. Spread half of the onion mixture evenly into the prepared pie shell. | 2. Arrange the tuna slices in a single layer over the onion mixture. | 3. Top with the remaining onion mixture, spreading it evenly.

1. Roll out another sheet of puff pastry and place it over the tart. | 2. Trim the edges by pressing the top and bottom crusts together with a rolling pin along the rim of the baking dish. | 3. If desired, create decorative patterns or cutouts on the top crust for ventilation and aesthetics.

1. Preheat your oven to 425°F (220°C). | 2. Bake the tart for about 30 minutes or until the filling is set in the center and the crust is golden and flaky.

Let the tart cool slightly before slicing. Serve warm and enjoy this savory masterpiece!