Prepare the oven and preheat it to 350 degrees F. Also, prepare a baking sheet by lining it with parchment paper.

Add salt, cinnamon, sugar, and butter in a small bowl until everything combines well.

Place the four slices of bread separately on the work surface, apply the butter mixture on top of each slice, and spread using a spoon or a knife.

Transfer the slices to the prepared baking sheet in a single layer and place in the oven; broil until slices turn golden brown and the sugar starts to bubble; avoid overcooking.

When slices are ready, remove them from the oven, slice diagonally and serve.