1. Preheat your oven to 400°F or 200°C to begin.

2. In a large mixing bowl, take the butter and sugar and cream them together until the mixture becomes light and fluffy. Next, beat in the eggs one at a time to ensure they're fully incorporated. Add the almond extract and almond paste to this mixture, blending everything well.

3. Now, in a separate bowl, whisk together the flour, baking powder, and vanilla sugar until the dry ingredients are well combined. Alternate adding the dry ingredients and milk to the butter mixture, mixing until just combined to avoid overmixing.

4. Take the batter and spread it evenly in a small, lined long pan, approximately 10x14 inches in size. Smooth out the top to ensure an even bake.

5. Place the pan on the lower rack of the oven and bake for about 25 minutes, or until a toothpick inserted in the center of the cake comes out clean. Once done, let the cake cool completely.

6. For the glaze, mix powdered sugar and water together until you form a thick, smooth glaze. Spread this glaze evenly over the cooled cake. Using a spoon or a piping bag, create syrup swirls on top of the glaze for decoration. Let the glaze set before slicing the cake into squares.