Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan or line it with parchment paper, and set aside.
In a medium mixing bowl, whisk together the gluten-free flour, cinnamon, salt, baking powder, and baking soda until well combined. Set aside.
In a large mixing bowl, cream together the softened butter, white sugar and brown sugar, until light and fluffy.
Add the eggs, one at a time, beating well after each addition. Add in the milk and vanilla extract and mix one more time. Fold in the mashed bananas until evenly distributed throughout the batter.
Add the dry ingredients into the wet ingredients and mix until just combined.
Pour the batter into the prepared baking pan and spread it out evenly with a spatula.
Bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Remove the cake from the oven and let it cool completely in the pan on a wire rack.
While the cake is cooling, prepare the cream cheese frosting. In a mixing bowl, beat together the softened cream cheese, confectioners sugar, softened butter, and vanilla extract until smooth and creamy.
Once the cake has cooled completely, spread the cream cheese frosting evenly over the top of the cake.
Decorate with sliced bananas.
Slice the cake into squares and serve.