Preheat oven to 350° F. Grease an 8" x 4 1/4" loaf pan and set aside.
In a mixer beat butter for 1 minute. Add in granulated sugar and brown sugar and beat on high for 3 minutes.
Add in eggs, vanilla, and sour cream. Mix until incorporated.
Mix in flour, cinnamon, cream of tartar, baking powder, and salt. Mix until blended.
Pour into greased bread pan. In a small bowl mix together 2 Tbsp sugar 1 tsp cinnamon. Sprinkle on top of batter and place in oven. Bake for 55-60 min. Let cool for 20 minutes and then remove from the pan. The bread can stay on the counter in an airtight container for 5 days.