In a large bowl, sift (or whisk) together flour, baking powder, cinnamon, and salt. Add walnuts and stir gently.
In a medium bowl, whisk eggs until combined. Add in bananas, zest, oil, sugars, and vanilla and whisk until well combined.
Add wet mixture to the flour mixture and fold, scraping bottom and sides, until just mixed. Do not overmix or banana bread will be tough.
Divide batter between two prepared loaf pans. Bake 35-40 minutes, until a toothpick comes out clean. Cool for 15 minutes, then transfer to a rack and cool completely.
Notes
Store in an airtight container on the counter for up to 4 days.