Preheat the oven to 350°F. In a large mixing bowl, combine the sugars, vegetable oil, eggs, molasses and vanilla extract and sour cream. Beat on medium speed until the well combined. Scrape down the bowl as needed.
In a medium-sized bowl, combine all remaining dry ingredients. Then, add half the dry ingredients to the batter followed half the milk and beat until it starts to combine.
Finally add the remaining dry ingredients, mixing on low speed while pouring in the milk and beating until all of the ingredients are well combined. Use a spatula to scrape down the sides of the bowl and stir the batter from the bottom to the top to ensure it’s well mixed.
Bake in a 9x13-inch pan at 350°F for 30-32 minutes. Test the cake for doneness by inserting a toothpick into the center of the cake. If the toothpick comes out clean, the cupcakes are done. Cool Completely.
For the Frosting:
Cut the butter into 1-inch blocks. Beat the butter for 1-2 minutes until it is slightly softened.
Then add the cream cheese and cream together for 2-3 minutes until they are fluffy and free of lumps, scape down the bowl occasionally.
Slowly add 2 cups of confectionary sugar, followed by the heavy cream, maple syrup and vanilla extract and beat until desired consistency is reached.
Add the remaining powdered sugar 1 cup at a time until desired consistency, at least 2 minutes.
The sour cream can be substituted with Greek Yogurt.