Preheat the oven to 325°F (162°C). Spray a 9×5-inch loaf pan thoroughly with nonstick spray.

In a small bowl, whisk together 1 1/2 cups graham cracker crumbs, 1/2 cup whole wheat pastry (or white whole wheat) flour, 1 teaspoon baking soda, 1/4 teaspoon cinnamon, and 1/2 teaspoon salt. Set the dry mixture aside.

In a medium bowl, mash the 4 very ripe bananas until mostly smooth; set aside.

In a large bowl, whisk the 2 eggs and 1/2 cup loosely packed brown sugar until smooth and slightly combined.

Add 1/3 cup canned coconut milk and 1/2 cup canola oil to the egg and sugar mixture; whisk until combined.

Stir the mashed bananas and 1 teaspoon vanilla extract into the wet mixture until evenly incorporated.

Gradually add the dry mixture to the wet mixture, stirring gently until just combined. Do not overmix.

Pour the batter into the prepared loaf pan and smooth the top. Place the loaf pan on a baking sheet.

Bake on the center oven rack for 75–85 minutes, or until the center is set (a toothpick inserted in the center should come out clean or with a few moist crumbs). If the top begins to brown too much (often around 45 minutes), loosely tent the loaf with aluminum foil for the remaining bake time.

Remove the pan from the oven and cool the bread in the pan for at least 30 minutes before removing and slicing.