Preheat the oven to 350º. Use a bit of butter to liberally coat the inside of a 9- or 10-inch Bundt pan. Sprinkle a bit of flour in the pan and turn to coat evenly, then tip out and discard any excess.
In a large bowl, use an electric mixer to beat together the 1 cup of butter and the sugar. Beat in the eggs one at a time, then beat in the vanilla and sour cream. Set aside.
In a medium bowl, whisk together the 2 cups of flour, the baking powder, baking soda, cinnamon and salt. Stir the dry mixture just until combined. Scrape into the prepared pan and spread so the top is even. Bake for 45 minutes, or until a wooden skewer inserted at the center of the cake comes out clean. Let cool for 10 minutes in the pan on a wire rack, then flip the cake out of the pan and let cool completely on the rack.
While the cake is cooling, make the glaze. In a small bowl, stir together the powdered sugar, milk and vanilla until smooth. When the cake is cool, transfer to a serving platter and use a teaspoon to drizzle the icing back and forth in a zig zag pattern across the top of the cake.