Cut a piece of parchment paper so it fits like a sling into your loaf pan and overhangs over the longer sides of your pan.  Spray your loaf pan with cooking spray and then place the parchment paper in so it sticks and then spray the top of the paper as well.  (If you're not sure what this step should look like, see photos in blog post for reference)  If you don't have parchment you can simply spray your loaf pan, or butter and flour it.  Set aside.

Preheat oven to 350°. Lightly spoon flour into dry measuring cups; level with a knife. Combine the flour, baking soda, and salt, stirring with a whisk. Place sugar and butter in a large bowl and beat with a mixer at medium speed until well blended (about 1 minute). Add the eggs, 1 at a time, beating well after each addition. Add banana, yogurt, and vanilla; beat until blended. Add flour mixture; beat at low speed just until moist. Spoon batter into an 8 1/2 x 4 1/2-inch loaf pan coated with cooking spray. Sprinkle brown sugar on top. Bake at 350° for 1 hour or until a wooden pick inserted in center comes out clean. Cool 10 minutes in pan on a wire rack; remove from pan. Cool completely on wire rack.