Pre-freeze the ice cream machine canister and a freezer safe container. This will limit the thawing when the cold ice cream base is added to the container. 

Slice the peaches in half and remove the pit. To make it easier, cross the indent on the top of the peach (extra points for freestone peaches) and you can rock the pit side to side to remove it. Then, continue to dice the peaches into small chunks. 

Place the peaches, heavy cream, dark brown sugar, corn syrup, and kosher salt in a blender, food processor or large bowl with an immersion blender. Blend until smooth and only small pieces of peaches remain. 

Strain the peach mixture into a large pot through a fine mesh sieve. This removes the peach peels. 

Heat the cream mixture in a large saucepan over medium-high heat until it boils, stirring occasionally to ensure the sugar dissolves. 

Place the egg yolks in a large bowl while the cream mixture heats. Add the sugar and whisk vigorously until lightened and increased in volume.

Once the cream mixture comes to a boil, slowly add the boiling cream to the egg mixture while whisking. This process is called tempering, and it allows the eggs’ temperature to slowly increase to that of the boiling cream without overcooking them.

Stir in the bourbon if using. 

Cover the base with plastic wrap and poke a few holes before placing it in the fridge. 

You will get the thickest base and creamiest ice cream if you cool it overnight. It is not necessary, and you can spin the base as long as it is cool to the touch. 

Churn in an ice cream machine according to the manufacturer's instructions. I always add the base with the machine running to limit the amount that freezes to the sides of the bowl.

Freeze until it is thickened and will hold its shape when scooped on a spoon. This will take 20-30 minutes depending on your machine.

Pour ice cream mixture into frozen freezer-safe containers or loaf pan. Cover the surface with plastic wrap and freeze overnight.