Preheat oven to 350°.
Sift flour and baking powder together in a medium bowl. In a separate bowl, combine grated cheese, eggs, sugar and milk, and beat together with an electric mixer until smooth. Add melted butter and mix to combine.
Add flour mixture in small increments, whisking together to combine in between. (Your batter should be thick and creamy.)
Pour batter into a greased 9″ pie pan and bake 25 minutes or until the center is dry when tested with a toothpick. Cool on a rack additional 15-20 minutes before removing from pan.
In a small skillet, melt 1/8 cup butter and add chopped plantains, cinnamon, and sugar.
In a small saucepan, melt rest of the butter and guava paste together over medium low heat, thinning with water throughout. Cook approximately10 minutes or until mixture is smooth and spreadable.
Assemble dessert pizza by spreading a generous amount of guava sauce on the Salvadorean quesadilla. Spoon sautéed plantains on top, sprinkle with plenty of queso fresco, and enjoy.