Butterscotch Filling

Ingredients

• 0.8 cup firmly brown sugar light packed
• 6 large egg yolks 
• 0.5 cup flour all-purpose
• 2 cups milk 
• 0.1 teaspoon salt 
• 2 teaspoons vanilla extract 

Equipment

• sauce pan
• whisk

Directions

1. Whisk together brown sugar, flour, and salt in a heavy saucepan; whisk in egg yolks and milk until well blended. Cook over medium-low heat, whisking constantly, 10 to 12 minutes or until a chilled pudding-like thickness. (
2. Mixture will just begin to bubble and will be thick enough to hold soft peaks when whisk is lifted.)
3. Remove from heat; stir in vanilla. Use immediately.