Preheat the oven to 350 degrees F. Grease the bottom and 1/2 inch up the side of a 9 by 4-inch bread pan.
Sift together the flour, baking soda, baking powder, salt, and cinnamon and set aside
In a medium bowl mix together the sugar, buttermilk, oil, and eggs. Once combined mix in the vanilla.
Add the dry ingredients to the wet ingredients and mix until combined. Pour the batter in the prepared bread pan.
In a small bowl combine the brown sugar, 2 tablespoons sugar, and 1 teaspoon cinnamon and mix together. Sprinkle the topping over top of the batter.
Place in the oven and bake for 50 to 55 minuter or until the wood pick comes out clean when inserted into the bread.
Remove from the oven and set on a cooling rack for 5 to 10 minutes, remove the bread from the pan and continue to cool on the cooling rack until cooled.
Once the bread is completely cooled mix together the powdered sugar, vanilla, and enough of the milk to make the right consistency for drizzling over the top of the bread.