Preheat the oven to 325°F (163°C). Position a rack in the center of the oven. Thoroughly spray a 9×5-inch loaf pan with nonstick spray and set it on a baking sheet.
In a small bowl, whisk together the graham cracker crumbs, whole wheat pastry flour, baking soda, salt, and cinnamon until evenly combined. Set the dry mixture aside.
In a large bowl, whisk the eggs and brown sugar until smooth and the sugar begins to dissolve.
Whisk the canned coconut milk and canola oil into the egg and sugar mixture until combined.
Mash the bananas in a separate bowl (if not already mashed). Stir the mashed bananas and vanilla into the wet ingredients until evenly distributed.
Add the dry ingredients to the wet mixture in batches, stirring gently and mixing only until just combined. Do not overmix.
Pour the batter into the prepared loaf pan and smooth the top. Place the loaf pan on the prepared baking sheet and put it on the center oven rack.
Bake for 75–85 minutes, or until the center is set and a toothpick inserted into the center comes out with only a few moist crumbs. If the top is browning too quickly, loosely tent the loaf with aluminum foil after about 30–45 minutes of baking.
Remove the pan from the oven and let the bread cool in the pan on a wire rack for at least 30 minutes before removing and slicing.