Step 1

If needed, place the bowl of the ice cream maker in the freezer at least 12 hours or according to manufacturer’s instructions before churning.

Step 2

Fill a large bowl with ice cubes and water. Place another smaller bowl on top of the water. Set aside while you make the ice cream base.

Step 3

Halve and pit 1 pound peaches (no need to peel), or arrange 1 pound frozen peach slices in a single layer on a baking sheet at room temperature for about 1 hour or until thawed, discarding any liquid that is released. Coarsely chop the peaches into rough 1-inch pieces and place in a medium saucepan.

Step 4

Use a vegetable peeler to remove a 1 1/2-inch long strip of zest from 1 medium lemon and add to the saucepan. Add 3/4 cup of the granulated sugar, 1 1/2 cups whole milk,1 1/2 cups heavy cream, and 1/4 teaspoon kosher salt. Split 1 vanilla bean in half lengthwise, scrape the seeds into the saucepan, and add the pod to the pan as well (or add 2 teaspoons vanilla extract instead).

Step 5

Bring the milk mixture to a simmer over low heat, stirring occasionally, until the mixture is warm and the sugar dissolved, 18 to 20 minutes. Meanwhile, place 4 large egg yolks and the remaining 1/4 cup granulated sugar in a medium bowl and whisk until combined, smooth, and pale, lemon-yellow in color, 2 to 3 minutes.

Step 6

When the milk mixture is ready, remove the saucepan from the heat. Temper the eggs by slowly adding 1/2 cup of the milk mixture into the egg mixture while whisking constantly. Repeat whisking in another 1/2 cup of the mixture mixture into the egg mixture.While whisking the remaining milk mixture, slowly pour the egg-milk mixture back into the saucepan. Place over low heat and cook, stirring or whisking constantly, until thick enough to coat the back of a spoon and about 170°F on an instant-read thermometer, about 2 minutes.

Step 7

Pour the mixture into the bowl set above the ice bath and let cool to room temperature, about 30 minutes. Pour through a fine-mesh strainer into an airtight container and discard the contents of the strainer. Cover and refrigerate for at least 3 hours or up to overnight.

Step 8

Churn the ice cream base according to manufacturer’s instructions until the ice cream has a soft serve consistency, usually 20 to 25 minutes.

Step 9

Quickly transfer the ice cream to a 1-quart freezer-safe food storage container. Press a piece of parchment paper or plastic wrap against the surface of the ice cream to prevent ice crystals from forming. Freeze until solid, at least 4 hours.