Place butter and oil in a small saucepan over low heat. Let the butter melt completely, but do not let it bubble aggressively. Whisk in cocoa powder until smooth and glossy.
Whisk in sugar and cook gently 1-2 minutes, then remove from heat. Immediately stir in chocolate morsels, vanilla extract, and salt. Let it sit 30 seconds, then whisk until fully smooth. Cool 10-15 minutes.
Roll out 1 sheet of thawed puff pastry on parchment paper until about 12 inches in diameter or ⅛" thick. Trace the outline of a 9" cake pan with a sharp knife, cutting the pastry into a large circle. Repeat the process with the other sheets.
You should now have 4 circular puff pastry sheets - a top and bottom piece for each of the 2 pastries. Spread the chocolate mixture over the 2 bottom sheets in a thin, even layer, bringing it close to the edges but leaving a small border.
Lightly crush freeze-dried raspberries into a powder with small flakes, avoiding large chunks. Sprinkle the raspberry powder over the chocolate mixture, gently pressing it into the filling with an offset spatula or clean hands. Reserve 2 teaspoon of raspberry powder for later.
Place the top layer of pastry over each round and lightly press to seal, ensuring there are no air bubbles. For each pastry, place a small glass in the center to mark a circle. Cut pastry from the outer edge towards the center circle, first into quarters, then eighths, then sixteenths.
Take two adjacent strips and twist them 2-3 times away from each other. Pinch ends together to form a point. Repeat all the way around for both chocolate puff pastries.
Preheat oven to 400°F. Refrigerate assembled chocolate pastries 10-15 minutes before baking. Whisk egg and 1 tablespoon water to form an egg wash, then lightly brush over the tops of the pastries, avoiding brushing heavy amounts into the cut edges. Bake for 15-20 minutes or until golden brown and fully puffed.
While pastries are cooling, about 10-15 minutes, whisk together powdered sugar, raspberry powder, and lemon juice. Slowly whisk in heavy cream until a thick ribbon consistency is achieved.
Drizzle pastries with raspberry glaze and additional crushed raspberries and enjoy!
Notes
Texture should be thick but spreadable like Nutella. If too thick, stir in ½ teaspoon warm milk. If too thin, let it cool longer.
Let the puff pastry thaw at room temperature for 30-45 minutes, or in the fridge for 3-4 hours before using.
Puff pastry loves cold conditions. If it becomes soft or sticky while assembling, you can put it back in the fridge for 5-10 minutes.
Don't let the chocolate mixture come to a boil. If you see bubbling around the edges, lower the heat immediately.
Try not to roll the puff pastry too thinly, or it will tear during the twisting process.
Store leftover chocolate pastries at room temperature for up to 2 days, loosely covered with foil or in a container that isn't airtight.
If you want to store them longer, you can refrigerate them in an airtight container up to 4-5 days, but the pastry will soften in the fridge.
To revive, bake leftover pastries at 300°F for 5-8 minutes.
You can freeze the assembled pastries for later use, then bake them when you're ready to enjoy!