Preheat the oven to 350F degrees. Line with parchment paper or grease and flour a large 9 x 5 inch loaf pan and set aside.In a medium bowl whisk together the flour, baking soda, cinnamon, nutmeg and salt. Set aside.Using a hand held or stand mixer on medium speed, cream the butter and sugar together in a large bowl (about 1-2 minutes). Add in the eggs and vanilla and continue mixing until combined (about 30 seconds).Turn off the mixer and scrape down the sides. Using a large rubber spatula or wooden spoon, fold in the yogurt and mashed bananas until incorporated. Then carefully fold in the flour mixture until just combined.Pour the batter into your prepared loaf pan and bake for 50 minutes to 1 hour. The edges should be just starting to pull away from the sides and an inserted toothpick should come out clean. If the top is starting to brown too much before its finished, cover loosely with aluminum foil and continue baking.