Preheat oven to 375℉ (190℃). Line a baking sheet with parchment paper.
Mash bananas with a spoon or puree them in a food processor or blender. Then add eggs, vanilla extract, and almond extract.
Combine cornmeal, sugar, flour, salt, grated orange zest, and baking powder in a large bowl, followed by the nuts.
Add the flour mixture to the banana mixture and stir until well blended.
Turn the dough out onto a lightly floured surface and knead lightly. Divide dough in half and flatten. Shape each portion into a log about 12 inches long and 1 inch thick. Place the rolls about 4-5 inches apart on a baking sheet.
Put the dough in the oven, lower the heat to 350℉ (180℃), and bake for 25-30 minutes. Transfer the logs to a cutting board and let cool for 10 minutes.
With a serrated knife, slice the logs crosswise into ½-inch slices for a total of 36 biscottis. Arrange the cookies in a single layer on the baking sheet. Lower the oven temperature to 300℉ (150℃).
Bake the biscotti for about 10 minutes per side, turning once as you bake. Transfer the biscottis to a wire rack. The biscotti will crisp as they cool.