1. Preheat oven to 225°F.

2. Line large baking sheet with parchment paper, set aside. 

3. Using a stand mixer fitted with the whisk attachment beat the egg whites on med/low until the beater begins to leave tracks. 

4. With the mixer on, gradually add the sugar, 1 Tbsp. at a time, waiting for the sugar to dissolve before adding more. 

5. Turn mixer to high speed and continue to beat until glossy stiff peaks form. 

6. Fold in lemon juice, bean paste, blackberry flavor, and cornstarch. 

7. Add meringue to large pastry bag fitted with a large star tip, taking care not to avoid making air pockets in the bag. 

8. Begin piping nests by staring in the middle and spiraling outward, 3 inches. Pipe a loop around the edge to create a dam for the filling. 

9. Bake at 225°F for 75 minutes. 

10. After the 75 minutes, turn off the oven and allow the Pavlova to continue to bake with the door closed for another 30 minutes. The outside should be dry and crisp.

11. After removing the Pavlova from the oven, transfer with the parchment paper to a cooling rack and cool to room temperature. 

12. If you will NOT be assembling right away, place Pavlova in airtight container to protect from humidity. 

13. Once you are ready to assemble, beat powdered sugar and cold heavy cream until stiff peaks form. 

14. Spoon cream into each Pavlova and top with berries. Serve within 4 hours of assembly.