For the Ice Cream Base:

1. Halve the vanilla bean lengthwise and scrape the seeds into a saucepot. Add the cream, milk, sugar, and salt and whisk to combine. Bring the mixture to a simmer, stirring occasionally to dissolve the sugar. Remove from heat.
2. Beat the egg yolks in a large mixing bowl. Slowly stream in the hot cream mixture, whisking constantly. Return the mixture to the pot and place over low heat.
3. Cook the custard, stirring constantly, until thickened (it should coat the back of a spoon).
4. Meanwhile, toast the marshmallows: line a large baking sheet with parchment paper, spray with nonstick cooking spray, and spread the marshmallows out in an even layer. Place an oven rack as close to the broiler as you can and then turn the broiler on. Toast the marshmallows under the broiler for 1-2 minutes, watching carefully the ENTIRE time. You want them golden and toasted, NOT burnt to a crisp. Remove from the broiler and allow to cool. Once slightly cool, place most (⅔) of the toasted marshmallows into a large bowl. Reserve the remaining marshmallows for mixing in later.
5. Strain the hot ice cream custard through a fine-mesh strainer into the bowl with the marshmallows. Whisk the mixture until the marshmallows have dissolved into the custard. Whisk in the vodka, cover the mixture with plastic wrap, and place in the fridge to chill for a few hours.
6. While the ice cream base is chilling, make your peanut butter caramel.

For the Caramel:

1. See this post for instructions. Cool caramel to room temperature before adding it to the ice cream.

Assembly:

1. Pour the chilled ice cream base into your ice cream maker and churn until the custard is just starting to firm up like soft serve ice cream (for me, this was about 10 minutes. Different machines will have varying times). Add the remaining toasted marshmallows one by one to the custard while the machine is churning. Continue to churn the ice cream to your desired consistency.
2. Transfer half of the ice cream to a container. Swirl in some of the peanut butter caramel, graham cracker crumbs, and chocolate shavings. Top that with the remaining ice cream and repeat again with caramel, crumbs, and chocolate. Try not to overmix everything; you want there to be swirls of caramel and chunks of graham and chocolate.
3. Cover the container and freeze until firm, at least 4 hours.
4. When you are ready to serve, allow the ice cream to soften for about 5 minutes before scooping. Serve in bowls or cones.