Whisk first 8 ingredients together in a heavy bottomed saucepan over medium heat.
Whisk constantly for 9-12 minutes until sauce has thickened. Do not walk away from the sauce.
Remove from heat and stir in vanilla.
Serve warm. To re-heat, place in a microwave safe bowl and re-heat for 2 minutes, stirring every 30 seconds.
See NOTES below about adding in alcohol.