Make the butter brickle bits: Melt butter and brown sugar in a pan, stir until caramelized, add nuts (optional), let cool, and break into small pieces.
Prepare the ice cream base: Mix milk, cream, sugar, vanilla, and a pinch of salt. Chill for 1 hour.
Churn the ice cream: Pour the chilled mixture into an ice cream maker and churn for 20–25 minutes.
Add the butter brickle bits: Stir in the cooled brickle pieces during the last 5 minutes of churning.
Freeze: Transfer to a container and freeze for 2–4 hours until firm.