In a medium-sized saucepan, mix together the brown sugar, cornstarch and salt (off the heat). Add the egg yolks and whisk until the starch is completely dissolved. Add the milk and whisk until smooth and everything has dissolved.

Transfer the saucepan to the stove and cook over medium heat, whisking constantly, until liquid thickens and comes to a bubble. When the first bubble appears, turn the heat to low and stir vigorously for exactly 1 minute. Take off the heat and stir in the butter, vanilla and butterscotch extract.

Transfer pudding to a bowl. Place plastic wrap directly on the surface of the pudding to prevent a skin from forming. Refrigerate at least 3 hours or overnight to chill completely. Just before serving, remove pudding form the fridge and whisk by hand or beat on medium speed just until smooth and creamy. Enjoy!