Preheat oven to 350°. In a large bowl, combine flour, sugar, baking soda, 1/2 teaspoon cinnamon and salt. In a small bowl, whisk egg, yogurt, oil and vanilla. Stir into dry ingredients just until moistened. In a small bowl, combine brown sugar and remaining cinnamon.
Spoon a third of the batter into an 8x4-in. loaf pan coated with cooking spray. Top with a third of the brown sugar mixture. Repeat layers twice. Cut through batter with a knife to swirl the brown sugar mixture.
Bake 45-55 minutes or until a toothpick inserted in the centre comes out clean. Cool 10 minutes before removing from pan to a wire rack.