Add all of the Cupcake ingredients to the bowl of your electric mixer and beat on low speed until just moistened (to prevent air bubbles) then increase speed to medium and beat for two minutes, scraping down the sides of your bowl as needed.

Divide batter evenly among 24 greased muffin cups (about two-thirds full) and bake at 350 degrees F for 18-22 minutes or until a tester inserted in center comes out clean. Cool cupcakes in pans on wire racks for 10 minutes; remove to wire racks to cool completely.

Meanwhile, prepare frosting by melting butter over medium low heat. Stir in brown sugar and bring to a boil, stirring constantly. Stir in heavy cream, cinnamon, vanilla and salt and return to a boil. Boil for 30 seconds, stirring constantly then remove pan from heat and cool until lukewarm, about 20 minutes.

Transfer butterscotch to the bowl of your electric mixer and add 1 tablespoon milk and powdered sugar and beat until combined. Add 1 more tablespoon milk and beat until smooth, adding additional milk a little at a time if needed to reach desired consistency (additional milk will depend on how much your butterscotch has thickened as its cooled - I use 2 tablespoons milk total). Note this frosting is smooth and silky, not light and fluffy.

Frost cooled cupcakes and sprinkle with sea salt.