Preheat oven to 350°F (175°C). Line a 9×5-inch loaf pan with parchment paper or grease it lightly.
Mash the bananas in a large mixing bowl until smooth.
Whisk in wet ingredients: Add Greek yogurt, honey, eggs, oil, and vanilla. Mix until well combined.
Mix dry ingredients: In another bowl, whisk flour, baking soda, baking powder, salt, and cinnamon.
Combine: Gently fold dry ingredients into wet mixture. Do not overmix — batter should be slightly lumpy.
Add mix-ins: Fold in chocolate chips or nuts if desired.
Pour batter into loaf pan and smooth the top.
Bake for 50–55 minutes, or until a toothpick inserted in the center comes out clean.
Cool in the pan for 10 minutes before transferring to a wire rack. Slice and serve warm or at room temperature.