1-Preheat oven to 350° and spray a: Preheat oven to 350° and spray a 9″ X 5″ loaf pan with nonstick cooking spray.
2-Grate the yellow squash: Grate the yellow squash.
3-In a large bowl whisk the flour,: In a large bowl whisk the flour, cinnamon, baking powder, baking soda and salt until combined; set aside.
4-Mix oil, sour cream, sugars, eggs, and: Mix oil, sour cream, sugars, eggs, and vanilla together in a medium bowl. Stir in grated squash. Add squash mixture into the dry ingredients and mix until just combined. Do not over-mix.
5-Pour batter into the prepared pan and: Pour batter into the prepared pan and bake about 1 hour, or until the top dries out and begins to crack, the loaf pulls away from the sides of the pan or a toothpick or cake tester comes out with only a few moist crumbs on it.
6-Let bread cool in the pan on: Let bread cool in the pan on a wire rack for about 30 minutes then take it out of the pan and cool completely.