Created by JostLori on February 1, 2014
Step 1: Preheat the oven to 350°F. Line cupcake pans with 24 paper liners and set aside.
Step 2: With an electric mixer, blend the cake mix, milk, melted butter, eggs, vanilla and cinnamon until well combined. Scrape down the sides of the bowl with a rubber spatula. Increase mixer speed to medium and beat 2 more minutes more, scraping the sides down again, if needed. The batter should look well combined.
Step 3: Divide the batter evenly among the muffin cups. Place the pans in the oven side by side.
Step 4: Bake until the cupcakes are golden brown and spring back when lightly pressed with your finger, about 15-20 minutes.
Step 5: Allow the cupcakes to cool in the pan for 10 minutes, then remove them to wire racks to cool completely, about 30 minutes.
Step 6: While the cupcakes cool, prepare the frosting. Place the butter in a large mixing bowl and blend with an electric mixer at low speed until fluffy, about 30 seconds.
Step 7: Add the powdered sugar, 3 tbsp. milk, vanilla and cinnamon. Blend with the mixer on low speed until the sugar is incorporated, about 1 minute. Increase the speed to medium and beat until light and fluffy, 1 minute more. Blend in up to 1 tbsp. milk if the frosting seems stiff.
Step 8: Spread or pipe the frosting on top of the cupcakes. Store the cupcakes, uncovered, in the refrigerator until the frosting sets, about 20 minutes.