This sweet pick-me-up is perfect for a hot day and is a great way to use your ice cream maker without a lot of advance prep. No need to make an ice cream base--simply whisk together a few basic ingredients and soon you'll have a frozen beverage that beats any creation from the neighborhood coffee shop. Crunchy chocolate-hazelnut pralines make the perfect topping.
Prepare an ice cream maker according to the manufacturer's instructions.
Whisk together the espresso, chocolate syrup, half-and-half and cream in a medium bowl until well combined. Pour into the ice cream maker and churn until the mixture is thickened with a slushy consistency, about 25 minutes, depending on your machine.
Meanwhile, line a baking sheet with parchment and spray lightly with cooking spray.
Put the sugar in a medium saucepan and add enough water to reach the consistency of wet sand, about 1/4 cup. Bring to a simmer over medium-high heat, swirling gently so it cooks evenly, until the sugar is melted and the mixture is dark golden-brown like maple syrup, about 5 minutes. Using a heatproof spatula, stir in the hazelnuts, salt and vanilla. Immediately transfer to the prepared baking sheet spreading into a thin, even layer. Let cool completely and break into large pieces (see Cook's Note).
Put the chocolate in a medium microwave-safe bowl and microwave in 30-second increments, stirring well after each, until melted and smooth, 1 to 2 minutes total. Using 2 forks, dip the cooled praline pieces in the chocolate and return to the baking sheet until the chocolate is set.
Dip the rims of 2 glasses in the remaining melted chocolate. Divide the frozen mocha mixture between the glasses, top with whipped cream and serve with the pralines on top.
If the pralines are taking a long time to cool you may transfer them to the refrigerator for a few minutes. You can do the same after dipping them in chocolate.