FOR TWO-LAYER CHRISTMAS TREE COOKIE CAKE:
1. In the bowl of an electric mixer, cream together the softened butter, sugar, and vanilla until well combined.

2. Add the eggs one at a time and mix until fully incorporated.

3. Gradually add the sifted flour, baking powder, and salt to the wet mixture. Mix just until the dough comes together. If the dough is sticky, add a bit more flour until it becomes smooth. (TIP: If you have two identical trays to bake both cookies, you can divide the dough and prepare them at the same time. If not, divide the dough in half and rollout one at a time)

4. Roll out the cookie dough on a silicone baking mat or parchment paper to approximately ¼-inch thickness. Make sure it's large enough to cut out your Christmas tree shape later.

5. Refrigerate the rolled-out dough for at least 30 minutes to firm it up. This will make it easier to cut.

6. Place your Christmas tree template on top of the dough and carefully cut around it using a plastic cookie cutter tool or a blunt butter knife. Make sure the edges are straight.

7. Remove the excess dough from around the Christmas tree shape and return the cookies to the fridge for at least 15 minutes. This helps them maintain their shape when baked.

8. Preheat your oven to 325°F (160°C).

9. Bake the Christmas tree-shaped cookies for 20-25 minutes or until they're cooked and lightly golden.

10. Remove the cookies from the oven and allow them to cool completely on the trays. Large cookies can be fragile when warm, so handle them carefully.

11. While Christmas tree cookies are cooling prepare your vanilla bean white chocolate cheesecake filling.

FOR WHITE CHOCOLATE CHEESECAKE FILLING:
1. In the bowl of an electric mixer, whip the softened cream cheese, sugar, and heavy cream on low speed until the ingredients are combined. 

2. Increase the speed to high and continue whipping until the sugar has completely dissolved, and the mixture is smooth and thick.

3. Meanwhile, melt the white chocolate on medium power in the microwave. Stir every 30 seconds until the chocolate is just melted. Be careful not to overheat the chocolate, as it can seize and become lumpy.

4. Pour the melted white chocolate into the center of the cheesecake mixture (avoiding the sides of the bowl) and whip until everything is well combined. 

ASSEMBLY:
1. Place one Christmas tree cookie on a serving platter or cake stand. Spread a thin layer of frosting on top.

2. Carefully stack another Christmas tree cookie on top of the first one, slightly offset to create a two-layer tree.

3. Continue layering and frosting until you've used all your cookies. Finish by frosting the entire tree.

4. Decorate with colorful icing, sprinkles, or edible decorations to make it festive.

5. Slice and serve your delicious Two-Layer Christmas Tree Cookie Cake as a centerpiece for your holiday celebrations!