In a medium sauce pan, turn the stove onto medium heat and melt the butter. Whisk in the brown sugar, then whisk in the heavy cream. Let the mixture bubble and thicken for 5 minutes without stirring. Remove from heat and whisk in the vanilla and salt.
Allow the butterscotch to cool before using.
BROWN SUGAR CUPCAKES
Preheat the oven to 350 degrees and line a cupcake pan with liners or spray with non-stick spray.
In a large mixing bowl, combine the flour, baking powder, baking soda and salt together. Whisk and set aside.
In a medium microwave-safe bowl, melt butter. Whisk in the brown sugar, stirring vigorously until there are no lumps. The mixture will be gitty.
Whisk in egg, yogurt, milk and vanilla until combined. Slowly pour the wet ingredients into the dry ingredients whisking together until no lumps remain. Batter will be thick.
Divide batter evenly between 12 cupcake liners. Place in the oven and bake for 20 minutes until a toothpick inserted in the center comes out clean. Allow to cool before filling or icing.
VANILLA BUTTERCREAM FROSTING
In a stand mixer, beat the butter on medium speed until smooth and creamy.
Add powdered sugar, cream and vanilla with the mixer on low. Increase to high speed and beat for 3-4 minutes.
Add more powdered sugar if too thin, add more heavy cream if too thick. If the frosting is too sweet, add a pinch of salt.
*Brown sugar can be used as a substitute but the cupcakes and butterscotch will come out slightly darker.
**This amount will depend on how thick you want the icing.