Preheat the broiler. Have ready a rimmed baking sheet.
In a small bowl, using a fork or rubber spatula, mash together the butter, honey, and cinnamon.
Arrange the bread on the baking sheet. Broil until the bread is toasted, about 1 minute. Remove from the broiler and flip the bread. Spread equal amounts of the cinnamon butter over the untoasted sides of the bread. Return to the broiler until the cinnamon butter is bubbling and the edges of the bread are toasted, about 1 minute. Serve hot.