Split the vanilla bean lengthwise and scrape out the seeds. Rub the seeds into a portion of the granulated sugar to separate and distribute them evenly. Set the pod aside for another use.
Place the vanilla-infused sugar and the remainder of the sugar in a mixer bowl together with the almond paste. Using the paddle attachment, add the butter gradually to avoid getting lumps in the batter. Cream the mixture together for a few minutes until it is smooth and light in color. Add the eggs, 1 at a time, scraping down the bowl as needed.
Sift the flour with the baking powder. Add the flour mixture to the batter on low speed, mixing just until it is incorporated.