Mayan chocolate cupcakes with chocolate cinnamon frosting

Recipe inspired by gimme some oven!
Oven temp = 350

Mayan chocolate cupcakes:
2 cups flour
1/2 cup unsweetened cocoa powder
1 1/3 cups sugar
1 1/2 tsp baking soda
1/2 tsp salt
1 1/3 cups water
1/2 cup vegetable oil
1 Tbs + 1 tsp apple cider vinegar
1 tsp cinnamon
1/2 tsp chilli powder
1/4 tsp cayene pepper

In a large mixing bowl, combine flour, cocoa powder, sugar, baking soda and salt. Mix in water, oil, vinegar, cinnamon, chili powder, and cayene pepper until everything is well combined. Pour into 22-24 cupcake papers and bake at 350 deg for about 25 minutes.

Chocolate cinnamon frosting:
1 stick (1/2 cup) butter, room temperature
1/2 cup unsweetened cocoa powder
1/4 cup milk
1 tsp. cinnamon
3 cups powdered sugar

In a large mixing bowl, combine the powdered sugar, cocoa powder, and cinnamon. Add half of the milk and the butter and beat together. Slowly add the remaining milk and beat until the desired fluffy consistency is reached.