Adjust oven rack to the lower-middle position, and pre-heat to 350°F.Grease a 9x5 loaf pan, dust with flour and tap out the excess.
spread the walnuts onto a baking sheet and toast in the oven for 5-10 minutes. set aside to cool.
Whisk the dry ingredients; Flour, sugar, baking soda, salt plus the walnuts in a large bowl and set aside
Mash the bananas and add the yogurt, eggs, butter and vanilla with a wooden spoon in a medium bowl. Lightly fold the banana mixture into the dry ingredients with a rubber spatula until combined and the batter looks thick and chunky. Scrape the batter into your loaf pan.
Bake until the loaf is golden brown and a toothpick inserted into the center comes out clean. About 55 minutes. Cool in the pan for 5 minutes, then transfer to a wire rack. Serve warm or room temperature. Once cooled wrap in plastic and store at room temperature for up to 3 days.