Heat oven to 350 degrees Fahrenheit. Coat muffin pan with coconut oil. Set aside.
In large bowl, whisk together bananas, oil, brown sugar, vanilla, and eggs until smooth.
In small bowl, gently stir flour, baking powder, salt and baking soda together with whisk; then stir into wet ingredients until just combined. Fold in chocolate chunks.
Evenly distribute batter into prepared pan. Bake for 20-25 minutes or until toothpick inserted in middle comes out clean.
Let muffins cool in pan a few minutes, then remove from pan onto a cooling rack until completely cool. Store in airtight container.
