Preheat the oven: Preheat the oven to 400°F. Line a large baking sheet with parchment paper.
Prepare the puff pastry: Allow the frozen puff pastry to thaw according to the package directions. Unfold the pastry sheets onto a lightly floured surface.
Cut out the ghosts: Using a ghost-shaped cookie cutter or a homemade template and sharp knife, cut the puff pastry into ghost shapes.
Make the ghost faces: Using round piping tips, cut two small circles for the eyes and a slightly larger opening for the mouth on every ghost. Carefully remove the excess dough.
Apply the egg wash: Arrange the ghost pastries on the prepared baking sheet, leaving space between each one. Lightly brush the tops with beaten egg, avoiding the facial openings.
Bake: Bake for 12–15 minutes, or until the puff pastry is puffed and golden brown. Remove from the oven and transfer to a wire rack to cool completely.
Prepare the chocolate whipped cream: In a chilled mixing bowl, combine the cold heavy whipping cream, unsweetened cocoa powder, Truvia Sweet Complete, and vanilla extract. Beat with an electric mixer on medium-high speed until stiff peaks form.
Slice the pastries: Once completely cooled, use a serrated knife to carefully slice each baked ghost pastry in half horizontally, creating a top and bottom layer.
Add the filling: Transfer the chocolate whipped cream to a piping bag. Pipe an even layer of filling onto the bottom half of each ghost pastry.
Assemble: Gently place the top half of each ghost pastry back over the chocolate whipped cream, allowing the chocolate filling to show through the cutout eyes and mouth. Serve immediately and enjoy!