Step 1: Preheat and Prepare

Preheat your oven to 350°F (175°C). Grease your baking pan with butter or oil and lightly dust with flour or line with parchment paper. This helps prevent sticking and ensures even baking.

Step 2: Mix the Dry Ingredients

In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon. Set aside.

Step 3: Cream the Butter and Sugars

Using a mixer, cream the softened butter, oil, granulated sugar, and brown sugar together until light and fluffy—about 3 minutes.

Step 4: Add the Eggs and Vanilla

Add in the eggs one at a time, beating well after each addition. Stir in the vanilla extract for a rich aroma and flavor.

Step 5: Mash and Mix the Bananas

In a separate bowl, mash the ripe bananas until smooth. Add them to the wet mixture along with the buttermilk. Mix until well combined.

Step 6: Combine Wet and Dry

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix. Fold in nuts or chocolate chips if using.

Step 7: Bake the Cake

Pour the batter into the prepared pan. Smooth the top with a spatula and bake for 35–40 minutes (for a 9×13 pan) or until a toothpick inserted comes out clean.

Step 8: Cool and Frost

Let the cake cool in the pan for 15 minutes, then transfer to a cooling rack. Once completely cooled, frost with cream cheese frosting if desired.