Prep your pan and oven. Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease the cups.

Make the flax mixture. In a small bowl, stir together the ground flaxseed and 3 tablespoons of the non-dairy milk. Let it sit for 5 minutes to thicken.

Mash the bananas. In a large mixing bowl, mash the bananas with a fork until mostly smooth with a few small lumps for texture.

Whisk in wet ingredients. Add the maple syrup (or coconut sugar), oil, remaining non-dairy milk, vanilla, and the thickened flax mixture. Whisk until well combined.

Combine dry ingredients. In a separate bowl, whisk the flour, baking powder, baking soda, cinnamon, and salt to evenly distribute the leaveners.

Bring it together. Add the dry mixture to the wet mixture. Stir gently with a spatula until just combined. Do not overmix—a few streaks of flour are okay.

Fold in add-ins. If using nuts, chocolate chips, or blueberries, fold them in now with 2–3 gentle strokes.

Fill the muffin cups. Divide the batter evenly among the 12 cups, filling each about 3/4 full. Sprinkle with turbinado sugar or oats if using.

Bake. Place on the center rack and bake for 18–22 minutes, or until the tops are set and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Cool. Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to finish cooling. This helps set the crumb and prevents sogginess.