Preheat oven to 350° F. Generously grease and flour a 9 x 5 inch loaf pan.
In a medium mixing bowl combine dry ingredients; flour, sugar, baking soda, baking powder, salt and 1 tablespoon cinnamon. Set aside.
In a large bowl whisk together the milk and lemon juice and let it stand for 5 minutes.
Add milk/lemon to the vegetable oil, vanilla and eggs. Stir to combine.
Add the wet ingredients to the dry ingredients and stir just until incorporated.
In small measuring cup stir together the brown sugar, 1½ tablespoons cinnamon and the melted butter.
Pour half of the batter into the prepared loaf pan.
Plop half the cinnamon sugar mixture by spoonfuls evenly onto the batter.
Use a skewer or toothpick to swirl the cinnamon mixture into the batter making "S" or "figure 8" shapes.
Repeat with the remaining batter and cinnamon/sugar mixture.
Swirl cinnamon/butter into the batter with the end of a skewer or toothpick. Making "S" or "figure 8" shapes.
Bake loaf for 70-80 minutes or until a toothpick inserted in the center of the loaf comes out clean.
Remove loaf pan from oven and cool on a rack for 5 minutes.
Remove loaf from the pan and allow to cool completely on wire rack.
Delicious toasted and served with butter.