We make a big batch of this classic Southern drink in the blender for easier entertaining. The blender creates a foam that you can spoon on top.
Combine sugar and 1/2 cup water in a small saucepan. Bring to a simmer over medium heat, stirring until sugar has dissolved. Remove from heat; let cool.
Combine milk, cream, vanilla, cinnamon, bourbon, 1 cup ice, and 2/3 cup simple syrup (reserve remaining for another use) in a blender. Blend until smooth, about 1 minute. Serve up in a chilled coupe or over ice in a rocks glass, spooning foam over the top. Sprinkle with nutmeg; serve immediately.