Add oat milk, egg yolks, honey, ground cloves and cinnamon to a blender and blend for 1 minute until smooth. Pour the mixture into a medium saucepan over medium heat and heat for 8 to 12 minutes, stirring constantly until thick and frothy (do not boil- you may need to lower the heat midway through cooking. Remove from heat and stir in vanilla extract.
Add the warm eggnog mixture to the hot espresso and serve immediately.
To make up to 1 day ahead, prepare the eggnog mixture but don't mix into the espresso. Let the mixture cool, then refrigerate in a mason jar or other airtight container. To serve, heat in saucepan until warm, stirring contantly, then mix into the hot espresso.
This nutritional information refers to each serving of the entire recipe and not just the products used as ingredients.