Toast the pecans in a skillet over medium heat until fragrant, about 5 minutes. Set aside.
In a saucepan, melt the butter and brown sugar together. Stir in the heavy cream, whole milk, vanilla extract, and salt. Heat until the mixture is warm but not boiling.
Let the mixture cool to room temperature, then refrigerate until cold.
Churn the mixture in an ice cream maker according to the manufacturer's instructions. Add the toasted pecans during the last few minutes of churning.
Transfer the ice cream to a container and freeze until firm, about 2 hours.