1) Adjust oven rack to lower middle position and preheat oven to 350˚F. Grease the bottom and sides of a loaf pan and dust with flour.
2) Whisk flour, sugar, baking soda and salt together in a large bowl and set aside.
3) Mash bananas and mix with yogurt, eggs, butter and vanilla.
4) Fold banana mixture into dry ingredients with a rubber spatula. Add the chocolate chips. Mix until just combined then scrape the batter into the prepared loaf pan.
5) Bake until the loaf is golden brown, and a toothpick inserted in the middle of the loaf comes out clean, about 55 minutes. Cool for 5 minutes in the pan. Serve at room temp.