Instructions

1. Preheat oven to 400 F (200 C). Set out 10 to 12 metal cone moulds, about 4¾-in (12 cm) tall × 1¼-in (3 cm) diameter at base.
2. On a clean work surface, roll puff pastry into a rectangle about ¼-in (0.6 cm) thick. Divide puff pastry into 2 parts if easier to work with. Using a sharp knife, cut pastry into 1-in (2.5 cm) wide strips.
3. Starting from base of 1 metal cone mould, wrap a pastry strip around mould, overlapping by about ¼-in (0.6 cm) from edge of previous strip each time around mould. Continue wrapping towards tip of cone. If pastry strip ends along the way, continue with another strip. Place prepared cone tip-side up in cavity of a muffin pan. Repeat to make 10 to 12 cones or until all pastry is used.
4. In a small bowl, whisk egg and water until combined. Using a pastry brush, brush egg wash over pastry cones.
5. Bake cones for 15 to 20 minutes, until golden brown. Remove from oven and cool slightly on a rack. Gently remove metal cone moulds and let cones cool completely. Can be stored in an airtight container at room temperature for up to 1 day.
6. In a shallow bowl, mix sugar and cinnamon.
7. Brush cones with melted better and dust with cinnamon sugar. Place cones tip-side up on a baking sheet.
8. Reserve 2 tbsp (30 ml) crushed pistachios for garnish. Place remaining pistachios in a small plate.
9. Spoon Eggnog Pastry Cream into a piping bag with a ½-in (1.25 cm) round nozzle tip. Pipe cream into prepared pastry cones, filling to brim. Gently press filled cones over plate of pistachios to coat base of cones, then place on a baking sheet. The pistachios will “seal” cones so they can be placed standing tip-side up or laid on their sides.
10. Place white chocolate in a small heatproof bowl over a small saucepan with simmering water, making sure bowl does not touch water. Stir until fully melted. Transfer melted chocolate to a small piping bag. Cut a small hole at tip of bag, about ¼-in (0.6 cm) in diameter. Pipe drips of chocolate from tip of each cone to slide gently down sides, then stand cones on a plate. Sprinkle wet chocolate with reserved crushed pistachios. Transfer cones to a serving platter standing tall like festive “trees” or laid on their sides.
11. In a medium saucepan over medium heat, bring eggnog, milk, sugar and salt to a simmer. Remove from heat.
12. In a medium bowl, stir egg yolks and cornstarch. Add a ladleful of warm eggnog mixture and briskly stir to temper eggs. Repeat this step. Slowly add tempered eggs to rest of eggnog mixture and return to heat. Continue cooking over medium heat, stirring constantly, until mixture thickens and first bubble pops. Remove from heat.
13. Add butter, vanilla, rum (if desired) and nutmeg. Stir until butter has melted and all ingredients are combined. Cover surface with plastic wrap to avoid a film forming. Cool slightly, then refrigerate for at least 4 hours and up to 3 days.