Combine butter, 3/4 cup brown sugar, and molasses in a medium saucepan. Cook over medium heat, stirring constantly, 5 minutes or until sugar dissolves.
Combine 1 3/4 cups milk and whipping cream in a separate saucepan. Split vanilla bean lengthwise. Scrape seeds from vanilla bean into saucepan; stir in bean pod. Bring just to a simmer over medium heat. Remove and discard vanilla bean pod. Slowly whisk milk mixture into sugar mixture.
Whisk together egg yolks, remaining 1/2 cup milk, cornstarch, vanilla, and salt in a small bowl. Gradually stir about one-fourth of hot mixture into yolk mixture; add yolk mixture to remaining hot mixture, stirring constantly. Cook over medium heat, stirring constantly, 20 minutes or until thickened. Remove from heat; pour into a 1-quart baking dish. Place plastic wrap directly on surface of pudding; chill at least 8 hours.
Combine 1/2 cup brown sugar, bourbon, and water in a small saucepan. Cook over medium-low heat 7 minutes or until a candy thermometer reaches 235°.
Meanwhile, beat egg whites and cream of tartar at high speed with an electric mixer until stiff peaks form. Gradually drizzle in hot brown sugar syrup, beating at high speed 2 minutes or until thick and glossy. Mound meringue over chilled pudding, forming peaks with the back of a spoon. Broil 8 inches from heat 2 minutes or until meringue is browned.