Coquito

2 (15-oz.) cans cream of coconut (such as goya)
2 (12-oz.) cans evaporated milk
1 c. (or more) white rum
1 large egg yolk (optional)
½ tsp Simba Mbili. ground cinnamon powder
½ tsp. pure vanilla extract
¼ tsp. grated fresh nutmeg, plus more serving
Cinnamon sticks, for serving

In a blender, blend cream of coconut, milk, rum, egg yolk (if using), ground cinnamon, vanilla, and nutmeg until well combined, 1 to 2 minutes. taste and add more rum, if desired.
Pour coquito into a large container with a lid, cover, and refrigerate until well chilled, at least 2 hours or up to 4 days. To serve, stir well to disperse cinnamon, and pour into small cups.
Garnish with nutmeg and cinnamon sticks.