In a large mixing bowl, stir together dry ingredients (flour, cinnamon, baking powder, baking soda, and salt. Add oil, honey, vanilla, and eggs, and stir until almost mixed. Add mashed bananas, frozen blueberries, and nuts and gently stir until just combined, being careful to mix in all of flour without overmixing.
Preheat oven to 350. Grease muffin tins with cooking spray and fill cups 3/4 of the way. Bake for 16-18 minutes, until a toothpick inserted in the center comes out clean. Cool for 5-10 minutes, run a knife around the edge of each muffin, and transfer out of pan. Enjoy immediately or cool on a cooling rack.
Store leftover muffins in refrigerator for up to 36 hours or freeze in gallon or quart bags for up to several months. Defrost muffins in refrigerator overnight to enjoy the next morning.
To make this recipe vegan, substitute out the eggs for flax eggs. In a small bowl, mix together 2 tablespoons ground raw flaxseed with 5 tablespoons of water. Let rest for 5 minutes and then add to batter in place of eggs.