In the bowl of your stand mixer, using the paddle attachment, cream the butter and sugars together for 3 minutes. Once butter and sugars are creamed, add egg. Blend thoroughly.
In a separate bowl, combine flour, baking powder, baking soda, salt, ginger, and cinnamon. Whisk together to fully combine. Set aside until ready to use.
Measure milk and molasses together; set aside. (I heat the milk and molasses mixture to help them combine easier.)
Add dry and wet ingredients (alternating) into the butter mixture until everything is fully incorporated.
Spray the inside of a 32-ounce ramekin with vegetable spray. Pour batter into the prepared ramekin. Place the rack into the Instant Pot and pour 1cup water into the bottom of the pot. Place the ramekin on top of the rack. Set it to Cake mode. Press start. When finished, let steam release naturally. Remove lid.