Whisk flour, baking powder, and salt in a small mixing bowl.
Beat the butter and sugar in a standing mixer (with the wire attachment) on medium-high speed until fluffy, about 5 minutes. Add eggs one at a time.
Turn down mixer speed to medium low; add half of the flour mixture, then all of the Salted Caramel milk.
Lastly, add the remaining flour mixture and blend until combined.
Fill cupcake liners about three-quarters full. The batter will rise as it's baked. Bake for 18 to 20 minutes or until a toothpick inserted into the center of a cupcake comes out clean.
Remove from oven and let cool 5 minutes. Then transfer cupcakes to a cooling rack. Let cupcakes cool completely before frosting.
To create frosting beat butter and shortening in a standing mixer with the paddle attachment until fluffy. Then slowly add powdered sugar, using a rubber spatula to clean the sides. Mix until fully incorporated.
Use a star shaped decorating tip to swirl icing on top. Lastly, drizzle the icing with butterscotch syrup. Enjoy!
You can store remaining buttercream in a sealed container in the fridge for up to 2 weeks. Sprinkle cupcakes with cinnamon sugar and enjoy with an ice cold glass of milk.