How to Make It
In a large saucepan, combine the Guinness with the cream and milk and bring to a simmer over moderately high heat. In a large bowl, whisk the egg yolks with the sugar. Gradually add the hot Guinness cream to the yolks, whisking constantly until well blended.
Pour the mixture into the saucepan and cook over moderate heat, stirring constantly until it coats the back of a spoon, about 6 minutes; do not let it boil. Pour the custard into a medium bowl set in a large bowl filled with ice water. Let stand until the custard is cold, stirring occasionally, about 30 minutes.
Pour the custard into an ice cream maker and freeze according to the manufacturer's instructions (this may have to be done in 2 batches). Pack the ice cream into an airtight container and freeze until firm, about 4 hours.
Spoon the ice cream into bowls and top with some Chocolate-Covered Pretzels. Serve at once.