Preheat oven to 350°F. Line cupcake pan with liners.
In a large bowl, mix butter and sugar; cream with an electric mixer until light and fluffy. Add eggs and beat well. Mix in vanilla.
In a separate bowl, sift together flour, baking powder, cinnamon, and salt. Add dry ingredients to the bowl with the wet ingredients a little at a time, alternating with root beer. Mix together until thoroughly combined.
Scoop batter into cupcake liners, bout ¾ full. Bake for 15-20 minutes, or until a toothpick inserted into the center of the cupcake comes out clean.
Cool cupcakes completely on a wire rack.
TO MAKE FROSTING:
In a deep bowl, cream softened (not melted) butter with hand mixer til light and fluffy. Add powdered sugar a little bit at a time, alternating with vanilla and root beer, until mixed.
Spread or pipe frosting onto cooled cupcakes and sprinkle with chocolate sprinkles, if desired.
Recipe by Food Fun Family at https://foodfunfamily.com/root-beer-float-cupcakes/