Preheat the oven to 350°F (175°C). Grease a 9x5 inch loaf pan with cooking spray and line the bottom with parchment paper.

Peel and mash the bananas in a medium mixing bowl with a fork or potato masher until mostly smooth with a few small lumps remain (about 1 1/2 cups).

In a large mixing bowl, whisk together the vegetable oil and granulated sugar until light and slightly pale, about 1 to 2 minutes.

Add the eggs one at a time to the oil and sugar mixture, whisking well after each addition. Stir in the mashed bananas and vanilla extract until combined.

In the medium mixing bowl, whisk together the all-purpose flour, baking soda, and salt until evenly distributed.

Pour the dry ingredients into the wet ingredients and gently fold with a rubber spatula until just combined, about 10 to 15 strokes (do not overmix).

Fold in the walnuts or chocolate chips if using. Pour the batter into the prepared loaf pan and smooth the top. Tap the pan on the counter to release air bubbles.

Bake for 55 to 60 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. The top should be golden brown.

Allow the bread to cool in the pan for 10 minutes, then transfer to a wire rack and cool completely (about 30 minutes) before slicing.