Pre-heat oven to 325F (160C). Grease and flour or spray an 8 inch / 20cm springform or regular cake pan.
In a small bowl mix together the brown sugar and cinnamon, set aside.
In a medium bowl sift together the flour, baking powder, baking soda and salt.
In a large bowl cream the butter and sugar, approximately 2-3 minutes, then add the eggs, beat until fluffy.
Add the dry ingredients alternately with the sour milk, ending with the sour milk to the creamed mixture. Add the vanilla and mix well.
Spoon 1/3 of the batter into prepared cake pan. Sprinkle with 1/2 of the cinnamon mixture. Spoon another 1/3 of the batter on top, then remaining cinnamon mixture, then top with the remaining batter. Bake for approximately 50-60 minutes or until toothpick comes out clean or with a few crumbs attached. Remove from oven and let cool 15-20 minutes in the pan then move to a wire rack to cool completely. Dust with powdered sugar before serving if desired. Enjoy!
Notes
To make sour milk - add 1 tablespoon lemon juice or white vinegar to 1 cup measure and top off with milk, let sit for about 10 - 15 minutes.To make homemade pastry/cake flour - for every cup of all purpose flour, remove two tablespoons and replace with two tablespoons of corn starch. Be sure to sift the flour and cornstarch together a couple of times, this way it is sure to be properly combined and lump free. Cake flour in cakes will give you a very tender texture and fine crumb, it will also help the cake to rise.For room temperature ingredients remove ingredients 45-60 minutes from the fridge before using. To store the cake - as long as the cake is unfrosted it should be kept at room temperature. Keep it in a cake container or well wrapped. It will keep for up to 3 days. If you store it in the fridge, wrap tightly to keep it from drying out. It will keep for up to 5-6 days in the fridge.To freeze the cake - be sure to cool the cake completely then wrap it tightly in either plastic wrap or foil, place it in a freeze safe bag. The cake will keep for up to 2 months. When ready to thaw place the wrapped cake in the refrigerator to thaw before serving.