Preheat oven to 350°F. Grease a 9x13 inch baking dish and set aside.

In a large bowl whisk together melted butter, Splenda, and allulose until both sweeteners are dissolved into the butter. Add vanilla and stir to combine.

Add bananas to bowl and use the whisk to mash and stir them into sugar mixture until well blended but still slightly chunky. Bigger banana pieces are super yummy.

Add flour, cornstarch, baking soda, and salt to wet ingredients. Using a wooden spoon stir to blend all ingredients until fully incorporated with no dry spots remaining, being careful not to over-mix.

Add chocolate chips, peanut butter chips, and mini marshmallows to dough. Fold in gently until just incorporated. Add in optional extra mix-ins here, too, if desired.

Spread dough out in an even layer in the prepared baking dish. Place in oven and bake 25-30 minutes or until a toothpick inserted in the center comes out clean. Mine generally only takes 25 minutes. Remove from oven and allow to cook at least 30 minutes before cutting. They are amazing served warm. Enjoy!