Using a paring knife, split the vanilla bean in half. Use the back of the knife to gently scrape the caviar out of the bean and into a large saucepan. Add the vanilla bean, half-and-half and sugar and heat over low heat, stirring occasionally, until the sugar has completely dissolved. Remove from the heat and set aside.
Whisk the egg yolks in a mixing bowl until pale yellow and slightly thick, 2 to 3 minutes. Temper the yolks by slowly drizzling a ladle of the hot half-and-half mixture into the bowl, whisking the whole time. Repeat with a second ladle of the hot half-and-half mixture, again whisking the whole time.
Pour the tempered yolks back into the saucepan with the remaining half-and-half mixture and cook over low heat, stirring gently with a wooden spoon, until it's thick enough to coat the back of the spoon, 3 to 4 minutes.
Set a fine-mesh strainer over a clean bowl. Pour the custard through the strainer into the bowl. Add the heavy cream to the strained mixture and stir everything together. Refrigerate until chilled, about 2 hours.
Pour the chilled mix into an ice cream maker and freeze according to the manufacturer's directions. Transfer to a freezer-safe container and place in the freezer until frozen firm, at least 6 hours (but overnight is best for nice scoopable ice cream). Serve on its own or with warm apple crisp.