I'm having a lot of trouble with the search mechanism here now that they've made so many changes :/ I want to find the best cinnamon vanilla cupcake recipe, and I know I've seen it I just can't reproduce my search results now! It's giving way too many posts with simply "cinnamon" and "vanilla" SOMEWHERE in the results!!! Yikes!
I do a cinnamon swirl cake that I just mix 1/2 cup of brown sugar with 2 tsp of cinnamon and swirl through vanilla cake batter before pouring into pan. Make sure that you only swirl 5 or 6 times with the spatula or it gets too incorporated.