Melt butter in a medium skillet over medium heat. Cook, stirring frequently, 2 to 3 minutes or until butter turns light brown and golden. Add pecans, and sauté to 2 minutes or until lightly browned and toasted. Remove pecans with a slotted spoon, reserving browned butter and pecans separately.
Bring milk, cream, and sugar to a boil in a medium saucepan over medium heat, stirring occasionally. Remove from heat, and stir in browned butter.
Beat egg yolks at medium-high speed with electric stand mixer until thick and pale (about 2 to 3 minutes). Gradually stir one-fourth of hot cream mixture into eggs. Add yolk mixture to remaining hot cream mixture, stirring constantly. Cook over medium-low heat, stirring constantly, 5 minutes or until a candy thermometer registers 170º and mixture lightly coats back of a spoon.
Pour mixture through a fine wire-mesh strainer into a bowl. Stir in bourbon, vanilla, and pecans. Cover and chill 1 hour.
Attach ice cream maker attachment to mixer according to manufacturer's instructions. Prepare ice cream according to manufacturer's instructions, using stir speed 1, for 15 to 20 minutes or until mixture reaches desired consistency. Serve immediately, or transfer to an airtight container and freeze to desired texture. Garnish, if desired.