Prepare the bread: Cut 2 slices thick white sandwich bread into a nine-square grid (3 vertical cuts and 3 horizontal cuts), making sure not to cut all the way through. Leave the base intact.
Make the honey butter: Melt 25g unsalted butter in the microwave for 20–30 seconds. Stir in 1 tbsp honey until smooth and glossy.
Brush the bread: Place the bread on a baking tray and brush the 25g butter + 1 tbsp honey mixture evenly over the surface of the bread, making sure it seeps into all cuts.
Add the sugar: Sprinkle 1 tbsp white sugar evenly over the bread and into the cuts. If using, mix 1 tbsp brown sugar with the 1 tbsp white sugar before sprinkling.
Bake the bread: Bake at 180°C fan-forced on the middle rack for 15–20 minutes, checking from 12 minutes. For fully crispy texture, bake closer to 18–20 minutes.
Cool and enjoy: Cool on the tray for 3–5 minutes until the caramelised sugar hardens. Pull apart and serve warm or at room temperature.