Prepare 2 slices of bread. Spread butter on one side of the bread, then add grated mozzarella cheese and top it with another slice of bread. Repeat until all the bread is used.

Cut the bread into 2 triangular pieces, then arrange them on a baking tray lined with baking paper.

Coffee mixture: Brew coffee with a small amount of hot water. Stir until well mixed, then let it cool to room temperature.

Top mixture: Mix butter with powdered sugar until evenly combined. Then add 1 egg and vanilla extract, and mix again until smooth. Add all-purpose flour and mix until well combined. The last, pour coffee mixture and mix again until well combined

Transfer the mixture into a piping bag, then pipe it onto the bread slices until all the bread is covered.

Bake the bread using the top heat element at 180 degrees Celsius for 20 minutes, and enjoy