Preheat the oven to 350 degrees F.
In a medium bowl, mash the softened butter with a fork. Add the sugar, cinnamon, and vanilla; stir to combine.
Spread the butter mixture on the bread slices.
Lay the cinnamon bread on a baking sheet and bake for 10 minutes. Then broil until golden brown and bubbling.
Remove from oven. Cut the slices into halves diagonally and serve.