Preheat & Prep:Begin by preheating your oven to 200°C (390°F) with both top and bottom heat. Line a baking sheet with parchment paper and place the 4 slices of toast on it, leaving a little space between them. Separate the egg and place the yolk in a small bowl; whisk it lightly with a fork until smooth.

Assemble the Base:Using a spoon or a small spatula, spread the salad dressing evenly over each slice of toast, covering the surface completely but using a light hand to avoid sogginess. Next, sprinkle the shredded cheese generously and evenly over the dressing, going all the way to the edges for maximum coverage.

First Bake (Melt the Cheese):Place the baking sheet in the preheated oven. Bake for about 10 minutes, or until the cheese is fully melted, bubbly, and just starting to show faint golden spots.

Add the Glaze & Final Bake:Carefully remove the tray from the oven. Using a pastry brush, gently brush a thin, even layer of the whisked egg yolk over the entire melted cheese surface on each toast. Immediately sprinkle the white sugar evenly over the glazed cheese. Return the tray to the oven and bake for another 5 minutes, or until the topping is a deep, appetizing golden brown and the sugar has caramelized. Let cool for a minute before serving—the cheese will be very hot!