In a medium saucepan, combine the milk, heavy cream, sugar, cocoa powder, and cinnamon. Place over medium heat, whisking frequently until the mixture is warm and the sugar has completely dissolved.

Once the milk mixture is warm, add the chopped Mexican chocolate (or dark chocolate) to the pan. Stir until the chocolate has completely melted and the mixture is smooth. You should notice the sweet and spicy aroma beginning to develop.

In a separate bowl, whisk the egg yolks with a pinch of salt. Gradually pour in about half of the hot chocolate mixture while whisking constantly (this is called tempering the eggs). This helps to gently warm the yolks without scrambling them.

Slowly pour the tempered egg yolk mixture back into the saucepan with the remaining chocolate mixture. Stir constantly and cook over medium heat for about 5–7 minutes until the custard thickens and coats the back of a spoon. Be sure to not let the mixture boil, as it can curdle.

For an extra smooth ice cream, you can strain the mixture through a fine mesh sieve to remove any curdled bits or lumps.

Once the mixture is thickened and smooth, remove it from the heat and stir in the cayenne pepper and vanilla extract. Allow the mixture to cool to room temperature, then cover it and refrigerate for at least 4 hours or overnight. This chilling step allows the flavors to meld together.

After the mixture has chilled, pour it into an ice cream maker and churn according to the manufacturer’s instructions. This process typically takes about 20–30 minutes, depending on your ice cream maker.

Once churned, transfer the ice cream to a container and freeze for an additional 3–4 hours to firm up before serving.