Preheat your oven to 350°F (175°C) and prepare a baking pan.
In a large mixing bowl, cream the softened butter and sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the vanilla extract and cinnamon, mixing well to combine.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually fold the dry ingredients into the wet mixture, alternating with milk.
If desired, fold in the currants or raisins gently.
Pour the batter into the prepared baking pan and smooth the top.
Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes before transferring it to a wire rack.