In a small pot, add your beer and spices.  Place the pot on low heat and heat just until warm.

While you're waiting for the beer to heat up, whisk your eggs and sugar until it turns pale yellow.

Add the egg mixture to the warm beer and put it back on medium to low heat.  With a rubber spatula, gently move the mixture back and forth in the pot to prevent the eggs from cooking.  You're looking for it to heat up to 75C-80C and no higher or the eggs with cook.

Maintain the temperature for a few minutes and you'll notice that it will start to thicken up.  Turn off the heat and add the butter.  Stir until melted.  You can use a milk frother to create some foam to top it off or if you're looking for something more decadent, add some whipped cream on top and enjoy!