Line an 8x8 inch square metal pan with parchment paper and set aside. Preheat the oven to 350℉. Mash the bananas and set aside. Melt the butter and as it cools, prep the rest of your ingredients.
1 cup bananas, 1/2 cup butter
In a large bowl, add melted butter, brown sugar, and white sugar. Whisk until smooth.
1/2 cup butter, 1/2 cup light brown sugar, 1/2 cup white sugar
Whisk in sour cream, bananas, egg, egg yolk, and vanilla. There may be chunks because of the banana, that is ok.
3/4 cups sour cream, 1 egg, 1 egg yolk, 1 tbsp vanilla, 1 cup bananas
Add in the flour, cinnamon, baking soda, cornstarch, and salt. Using a spatula, gently fold until a soft batter forms.
2 1/2 cups all-purpose flour, 2 tsps baking soda, 1 tsp cinnamon, 2 tsps cornstarch, 1/2 tsp salt
Add in the pecans and toffee and mix in a few times until well incorporated. Don’t overmix!
1/4 cup toffee bits, 1/4 cup pecans
Transfer the batter into your pan and spread. Sprinkle with extra toffee and pecan pieces. Bake for 35-45 minutes. A toothpick inserted in the middle will come out mostly clean. If it it wet with batter, the squares are not ready yet, so continue baking.
When ready, remove from the oven, cool, and enjoy!