Preheat oven to 325°F (160°C).

Cream powdered sugar and butter at room temperature with a mixer until light and fluffy.

Add eggs one at a time, beating well after each addition.

Stir in rum flavoring.

In a separate bowl, combine 3 cups of sifted flour and baking powder.

Gradually add the flour mixture to the creamed mixture, mixing with a large spoon until just combined. Do not overmix.

If the batter seems too thick, add the remaining sifted flour as needed, depending on weather and humidity.

Pour batter into a greased and floured loaf pan.

Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean.

Let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.