Preheat oven to 325°F. Grease two 8½ x 4½-inch loaf pans; set aside.
In a large bowl, whisk together flour, dry pudding mix, cinnamon, baking powder, baking soda and salt.
In a separate bowl, whisk together eggs, oil, sugar, buttermilk and vanilla extract.
Add the wet ingredients to the dry ingredients; mix just until combined (do not over-mix).
Divide the mixture evenly between the two prepared loaf pans.
In a small bowl, combine the sugar and cinnamon topping. Sprinkle over the two loaves.
Bake at 325°F for 1 hour, or until a toothpick inserted in the center of a loaf comes out clean.
Cool in the pan for about 10 minutes, then transfer to wire racks to cool completely before slicing and serving.