Directions

1. Preheat an oven to 350 degrees F (175 degrees C).
2. Line 24 muffin cups with paper liners.
3. Beat together the chocolate cake mix, 1 cup milk, eggs, 1/2 cup melted butter, 1 teaspoon cinnamon, and 1 teaspoon vanilla extract in a bowl with an electric mixer on low speed until moist. Beat for 2 more minutes on medium speed.
4. Fill each muffin cup about 2/3 full of batter.
5. Sprinkle the cupcakes with cinnamon sugar.
6. Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 15 minutes.
7. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
8. Cream together 1/2 cup butter and shortening in a bowl until smooth.
9. Stir in sea salt, 1 teaspoon vanilla extract, 1 tablespoon cinnamon, cocoa powder, and 3 cups confectioners' sugar.
10. Stir in milk.
11. Mix in 2 more cups confectioners' sugar or as needed until desired consistency is achieved.
12. Spread the frosting on the cooled cupcakes.