Preheat your oven to 350°F (175°C). Proper preheating is critical for consistent baking; placing your batter in a cold oven can alter the texture and rise of the bread.

Grease a 9x5-inch loaf pan with butter or cooking spray, ensuring you coat all sides and corners thoroughly. Alternatively, line the pan with parchment paper for easy removal.

Measure out the flour (2 cups) into a large mixing bowl, using a spoon to loosen and level it for accuracy.

Add the sugar (¾ to 1 cup) into the same bowl.

Incorporate the baking soda (1 teaspoon) and, if desired, baking powder (½ teaspoon).

Sprinkle in the salt (½ teaspoon) and ground cinnamon (1 teaspoon).

Whisk or stir the dry ingredients together until they’re well blended. This step ensures even distribution of leavening agents and flavors.

Mash the bananas in a medium bowl until relatively smooth. Some small lumps are acceptable, but aim for a cohesive consistency.

Grate the zucchini using the side of the grater with medium-sized holes. If the zucchini is exceptionally watery, give it a light squeeze to remove some excess moisture.

Crack the eggs (2 large) into the bowl with the bananas. Lightly beat to combine.

Add the vegetable oil or melted butter (½ cup) to the banana-egg mixture.

Pour in the vanilla extract (1 teaspoon) to round out the flavors.

Gently stir all the wet ingredients until they form a unified mixture.

Create a well in the center of the dry ingredient mixture.

Pour the wet ingredients into this well, stirring gently with a spatula or wooden spoon until the batter just comes together. Overmixing can lead to a tough loaf, so aim for a few small streaks of flour to remain before adding the zucchini.

Fold in the zucchini (1 cup grated). At this stage, if you’re using optional add-ins like chocolate chips or chopped nuts, gently fold them into the batter as well.

Inspect the batter to ensure it looks uniformly combined, but avoid heavy stirring once all the elements are together.

Carefully pour the batter into the greased or parchment-lined loaf pan, using a spatula to spread it evenly.

Tap the pan lightly on your countertop to remove any trapped air bubbles.

Place the pan on the center rack of your preheated oven and bake for 50–60 minutes. You’ll notice your kitchen filling up with a sweet, cinnamon-banana aroma.

Check for doneness by inserting a toothpick or skewer into the center of the loaf; it should come out clean or with only a few moist crumbs attached. If the top starts browning too quickly, tent it with aluminum foil to prevent over-browning.

Remove the loaf from the oven once fully baked and allow it to cool in the pan for about 10–15 minutes.

Carefully transfer the bread from the pan onto a wire rack to cool completely. This step helps maintain its shape and final texture.

Slice and serve when the bread is at room temperature. If you cut into it too soon, you risk a crumbly texture and an underdone center.