In medium bowl, cream together butter and granulated sugar until light and fluffy. Beat in eggs, one at a time, mixing until fully incorporated. Stir in vanilla.
Combine flour, baking powder and salt. Stir into batter alternately with milk. If batter is too stiff, add a tablespoon or more of milk.
Spread batter evenly into cake pan. Bake 30-35 minutes until a toothpick inserted in center comes out clean. Cool 10 minutes.
Meanwhile, combine powdered sugar and cinnamon. Remove cake from pan onto serving plate. Using a sifter, dust with sugar/cinnamon mixture and serve. It’s great warm with butter.