To prepare ice cream, combine 4 cups milk and 1 cup half-and-half in a large, heavy saucepan; bring to a boil.
Combine granulated sugar and 4 egg yolks; beat with a mixer at high speed until thick and pale. Gradually add half of hot milk mixture to yolk mixture, stirring constantly. Return milk mixture to pan. Cook over medium-low heat 2 minutes or until a thermometer registers 160°, stirring constantly with a whisk. Remove from heat. Place pan in a large ice-filled bowl. Cool completely, stirring occasionally. Pour mixture into the freezer can of an ice-cream freezer, and freeze according to manufacturer's instructions.
To prepare filling, combine corn syrup, brown sugar, cornstarch, and salt in a medium, heavy saucepan, stirring well with a whisk.
Combine 1 cup half-and-half, 1/2 cup milk, and 2 egg yolks, stirring well. Add milk mixture to sugar mixture; stir well with a whisk. Place pan over low heat; cook 12 minutes or until thick and bubbly, stirring constantly. Remove from heat; stir in pecans, butter, and vanilla. Transfer filling to a bowl. Place plastic wrap directly over filling; chill.
Spoon ice cream into a freezer-safe container; gently fold filling into ice cream. Cover and freeze 1 hour or until ice cream is firm.
Preheat oven to 350°.
To prepare garnish, place dough on a large cutting board or work surface. Cut 14 stars with a (1-inch) star-shaped cookie cutter. Place stars on a baking sheet coated with cooking spray. Bake at 350° for 12 minutes or until browned. Serve with ice cream, if desired.