Adjust oven rack to lower middle position and preheat oven to 350 degrees.
Spray 9-by-5-by-3-inch loaf pan with nonstick spray and line with parchment paper that hangs over the edge of pan. Spray parchment paper; set aside.
Whisk together flour, sugar, baking soda, salt and cinnamon in medium bowl; set aside.
In large bowl, mix mashed bananas with eggs, melted butter, and vanilla. Fold in walnuts and 3/4 cup chocolate chips.
Add dry ingredients into wet ingredients with spatula until just combined (do not overmix which will make bread dense). Scrape batter into prepared loaf pan and sprinkle top with remaining 1/4 cup chocolate chips.
Bake 55 – 65 minutes or until loaf is golden brown and toothpick inserted in center comes out clean with no batter (melted chocolate on toothpick is fine). During last 10 - 15 minutes of baking time, cover top of bread with foil to prevent overbrowning if needed.
Cool in pan for 5 minutes, then lift bread from pan using parchment paper and transfer to wire rack to cool. Serve warm or at room temperature.