1/2 cup espresso (about 4 shots)
1 1/2 cups whole milk
1 1/2 cups heavy cream
5 egg yolks
1 cup sugar
1 teaspoon cinnamon
1 teaspoon espresso powder
Reduce espresso and heat cream
Pour espresso into small saucepan and cook over medium heat (slow simmer) to reduce. This will take about 10 minutes or more to reduce by 1/2 or 1/3. Meanwhile, add the milk and cream to a medium saucepan and heat over medium heat until simmering. Remove from heat.
Add hot cream egg mixture, return to heat and add espresso shots/powder
In an electric mixer, whisk the eggs, sugar and cinnamon until light and fluffy. While this is mixing, slowly add the hot cream base. Continue to mix until mixture is well blended and then return this mixture to saucepan. Don't worry if the mixture gets a little frothy, it will settle down during heating. Cook over medium-high heat, stirring constantly until mixture thickens and a finger drawn across the back of a wooden spoon leaves a trace. Remove from heat and pour mixture through a chinois to remove any lumps. Add the espresso powder and blend until completely dissolved. Place the mixture in an ice bath and chill.
Freeze ice cream
Once the custard mixture has cooled to about 45° F, pour into ice cream maker. Freeze ice cream according to your ice cream maker's instructions and then transfer to a dedicated, smell-free container to let ripen in the freezer for several hours.