Prep dry lentils according to package instructions. I usually do up a bunch and then freeze them in 1 cup portions so they're ready for recipes like this.
Preheat oven to 300 degress.
Spray a 9x9 baking pan with cooking spray.
In a mixing bowl cream softened butter and sugar together.
In a blender combine cooked lentils, eggs, bananas, Greek yogurt, vanilla, and cinnamon. About 20 seconds on varying speed. You want the lentils and bananas fully broken down without the mixture becoming frothy.
Add blender mixture to the creamed butter and sugar. Combine.
In a separate bowl, combine dry ingredients. Slowly add to the wet mixture until everything is fully incorporated.
Pour batter into greased pan and bake for 50-60 minutes or until a toothpick comes out clean from the center.