Square deviled eggs

Ingredients:

• 12 large eggs
• 1/3 cup mayonnaise
• 1 tbsp. white vinegar
• 2 tsp. yellow mustard
• Paprika and chopped chives, for serving (optional)
• Special equipment: pastry bag with a small round tip

Preparation:

1. Preheat oven to 350°F (175°C). Spray an 8-inch square baking dish with cooking spray.
2. Separate the yolks from the whites and place them in 2 bowls, setting the yolks aside. Whisk the whites until foamy, pour them into the prepared baking dish, cover the dish with foil, and bake until the whites are completely set, about 20 minutes. Let cool completely in the dish.
3. While the whites are baking, beat the yolks until smooth. Lightly spray a medium nonstick skillet with cooking spray. Add the yolks and cook, stirring, over medium-low heat until set and the yolks are dry, 4-5 minutes.
4. Place the yolks in a food processor. Add the mayonnaise, vinegar, mustard, 1/4 teaspoon of salt, and a pinch of ground black pepper, and process until smooth. Transfer the yolk mixture to a pastry bag fitted with a small round tip.
5. Remove the egg white from the pan onto a cutting board. Cut into 2.5 cm squares. Pipe a yolk onto each square. Sprinkle with paprika and chives, if desired.