Combine the hot coffee and chocolate syrup in a cup and stir well. Set aside to cool to room temperature.

In a small pitcher, combine the marshmallow fluff, half & half, and vanilla extract. Using a coffee frother, froth the mixture until light and fluffy but still pourable.

Pour some chocolate syrup onto a plate and dip the rim of a latte glass in the syrup. Fill the glass with ice. Pour in the coffee mixture; top with the cold foam and garnish with chocolate shavings.