Snickerdoodle Cupcakes

Snickerdoodle Cupcakes
(these can be made into a cake too- whichever you prefer)
1 package plain white cake mix
1 cup whole milk
1 stick of butter, melted
3 large eggs
1 teaspoon vanilla extract
2 teaspoons ground cinnamon
Frosting:
1 stick butter
3 3/4 cup confectioners sugar
3-4 Tablespoons milk
1 teaspoon vanilla extract
1 Tablespoon ground cinnamon
Preheat oven to 350 degrees and flour & grease [...]