Using a stand mixer with a whisk attachment or a hand mixer, beat egg yolks on high until they are creamy and lighten in color (approximately 2 minutes).
Reduce speed to medium and slowly pour in maple syrup.
Continue beating over medium or medium-low and pour in coconut milk, bourbon, vanilla, and nutmeg.
Once everything is well combined, pour into bottle, jar, or pitcher with a tight-fitting lid and chill for a few hours or overnight. Alternately, if you prefer your eggnog at room temperature, you can consume it right away! I like it both ways, but prefer it nice and cold.
When ready to serve, beat egg whites until you get soft peaks. Make sure your bowl and whisk attachment are really clean and don't have any oils on them because this will prevent your whites from whipping up correctly.
Fold egg whites into the cold eggnog. I like to do this in a pitcher using a silicon spatula.
Serve in glasses and top with toasted coconut and more freshly grated nutmeg.
Store leftover eggnog under refrigeration with a tight-fitting lid and shake well before serving.