In a medium heavy-bottomed saucepan, combine milk, cream, half the maple syrup (about 3 tablespoons), vanilla, nutmeg, cinnamon, and salt. Heat over medium-low heat, stirring occasionally, until mixture reaches 160°F (71°C) and is steaming but not boiling.

In a large mixing bowl, whisk egg yolks with remaining maple syrup until pale and slightly thickened, about 2 minutes with electric mixer on medium speed.

Remove hot milk mixture from heat. Slowly drizzle about 1/2 cup of the hot milk into the egg yolk mixture while whisking constantly to temper the eggs and prevent curdling.

Continue adding hot milk in a thin stream, whisking continuously, until all milk is incorporated into the egg mixture.

Pour the entire mixture back into the saucepan and return to medium-low heat. Stir constantly with whisk until mixture thickens slightly and coats the back of a spoon, reaching 160°F (71°C). Do not let it boil or eggs will scramble.

Immediately strain the eggnog through a fine-mesh strainer into a clean bowl to remove any lumps. Cover with plastic wrap directly touching surface to prevent skin formation.

Refrigerate for at least 2 hours or until completely chilled. Stir before serving and adjust sweetness if needed.

Optional: Beat egg whites to soft peaks and gently fold into chilled eggnog for extra richness. Serve in chilled glasses with a dusting of nutmeg and cinnamon stick stirrers.