Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking powder, cinnamon, and salt.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Begin and end with the dry ingredients.
Pour the batter into a greased and floured cake pan.
Bake for 30 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely.