How to Make It
Melt butter in a small heavy saucepan over medium-high heat. Simmer about 4 minutes or until butter turns light brown and the milk solids on bottom of pan release brown specks. Set aside; let stand until just warm.
Combine milk, cream, and sugar in a medium saucepan over medium heat; bring to a low boil, stirring occasionally to dissolve the sugar. Remove from heat.
Beat egg yolks in a medium bowl with an electric mixer on medium speed 1 minute. Slowly add brown butter with specks into yolks, and beat 2 minutes or until mixture is thick and fluffy.
Slowly pour one-quarter of hot cream mixture into the egg mixture, stirring until incorporated. Pour this mixture back into the medium saucepan; add remaining hot cream mixture over low heat, stirring constantly with a heat-resistant spatula until mixture reaches 170° and lightly coats the back of spatula. (Be careful not to let the custard boil or the egg yolks will curdle.) Strain custard into a bowl through a medium-mesh sieve. Refrigerate custard 1 hour or until chilled; stir in the extracts.
Pour mixture into a 1 1/2-quart freezer container. Stir in chopped pecans, and freeze mixture according to manufacturer's instructions. Freeze 4 to 6 hours before serving.