First Step: Prepare the Pistachio Cream Filling. Begin by slightly roasting the shelled pistachios if not already roasted; this enhances their flavor. In a food processor, combine the roasted pistachios and milk powder. Process for 3 to 4 minutes until the mixture becomes fine and moist. While blending, slowly drizzle in the vegetable oil to create a silky smooth cream. Next, add the powdered sugar and blend until the paste is homogeneous. Transfer this rich pistachio cream into a pastry bag fitted with a fine filling tip. Chill for 10-15 minutes if the cream feels warm to ensure better piping consistency.

Second Step: Make the Simple Syrup Glaze. In a small saucepan, combine 1/2 cup of powdered sugar with 1/3 cup of water. Bring to a boil, then reduce heat and let simmer for 4 to 5 minutes until slightly thickened. Remove from heat and allow to cool.

Third Step: Assemble the Pastries. Take each baked cornetto or croissant and, using the pastry bag, insert the filling tip at a 45-degree angle into the bottom side of the pastry. Gently pipe the pistachio cream inside until evenly distributed. Arrange the filled pastries upside down for a few minutes to let the cream settle evenly within the pastry shell.

Fourth Step: Add the Finishing Touches. Brush the exterior of each stuffed delight with the prepared simple syrup glaze. Immediately roll or sprinkle the pastries with the chopped pistachios so they coat the surface generously. This step adds a glossy finish and crunchy contrast.

Final Step: Serve and Enjoy. Serve your decadent pistachio cream stuffed delights fresh for the best texture and flavor experience. They work wonderfully warm or at room temperature, making them perfect for breakfast, dessert, or a luscious snack.