Preheat your oven to 180°C (350°F) with both the top and bottom heat elements on.
In a mixing bowl, mash 3 ripe bananas (about 1 1/3 cups mashed), and mix them with 1 tablespoon neutral oil, 6 tablespoons applesauce, 100 ml sugar-free vanilla soy milk, and 1 tsp vanilla extract until well combined. Use a potato masher or fork for this step, being careful not to over-mash to avoid a dense texture.
Add the dry ingredients to the bowl: 225 g (about 1 3/4 cups) of flour, 190 g of stevia sugar substitute (equivalent to 1 cup of regular sugar), 2 tsp baking powder, ¼ tsp salt, and 1 tbsp cornstarch. Stir the batter until all the ingredients are fully incorporated.
Pour the batter into a loaf pan, ensuring it's evenly distributed. A loaf pan approximately 23-25 cm long works well for this recipe. If you're choosing to add nuts or chocolate chips, add them in and stir with a spoon to incorporate them into the batter.
Place the pan in the preheated oven and bake at 180°C (350°F) for about 60 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the banana bread from the oven and let it cool in the pan for a few minutes before transferring it to a wire rack to cool completely. Enjoy your WW banana bread!