In a small bowl, start by making the syrup. In a small saucepan, add your butter, add the pineapple juice, ground cinnamon, and brown sugar, mix well until the syrup is set.
Place butter into a springform pan, pour the syrup on top, add your pineapple slices, then add your maraschino cherry in the middle of the pineapple.
To make your cake, mix the butter, brown sugar, granulated sugar until they are creamed together.
Add the egg, and then mix in the flour, baking powder, salt, and milk. Pour the cake mix into the springform pan on top of the pineapple slices.
Wrap your springform pan in aluminum foil, then add the trivet to the Instant Pot bowl, add 1 cup of water to the Instant Pot. Set your pan onto the trivet. Set the manual high pressure for 55 minutes. When the time is up, do a natural release.
Let cool before serving.
Plate, serve, and enjoy!