Brown Sugar Coffee Cake requires surprisingly few ingredients and is amazingly delicious. It is so moist and easy you'll be making it all the time.
Preheat oven to 350. Mix together the brown sugar, flour and cinnamon. Using a pastry cutter, add the butter until the mixture has the texture of very fine crumbs. Remove one cup of the mix and set aside to be used as a topping.
Make the sour milk and let stand 5 minutes. Add baking soda to the sour milk.
Add the egg and sour milk and beat until smooth. Pour mixture into a greased pan (11 x 7) topping with the reserved mixture. Bake for 30-35 minutes. Note that cooking times may vary by oven.
Making sour milk is extremely easy. Add 1 T vinegar (or lemon juice) to a measuring cup and fill to the 1 c marker with milk. Let stand for 5 minutes.