Preheat the oven to 325 degrees F (160 degrees C).
Beat the Granulated Sugar (1 1/4 cup) with the Almond Paste (7 ounce) until the almond paste is in fine pieces. Or, better, pulverize it in a food processor.
Beat in the Unsalted Butter (1 cup), Vanilla Extract (1 teaspoon) and Almond Extract (1/8 teaspoon) if using, then cream the mixture until it is light and fluffy.
Beat in the Egg (6), one at a time, beating well after each addition so the eggs are thoroughly mixed in.
Mix the All-Purpose Flour (1 cup), Baking Powder (1 1/2 teaspoon), and Salt (1/4 teaspoon), and beat in just until thoroughly blended.
Butter a 9-inch springform pan and turn the batter into it, smoothing the top evenly. Bake for 1 to 1¼ hours (mine baked for 1¼ hours) or until a toothpick inserted in the center comes out clean and the center feels springy when you push it gently.
Let cool for about 20 minutes before releasing the sides of the springform pan. Add Powdered Confectioners Sugar (to taste), if preferred.