To make the meringue, beat the Egg (3) on low speed using an electric mixer until it is white and frothy, approximately 1 minute.
Gradually add the Caster Sugar (135 gram) 1/4 at a time. When the first addition of sugar has completely dissolved, increase the mixer speed to medium and add until all the sugar has been incorporated. Continue to beat until stiff peaks form.
Divide the meringue into 3 equal portions, and add to 3 separate bowls of Almond Meal (60 gram) and Powdered Confectioners Sugar (60 gram).
In one bowl, add Orange Food Coloring (to taste). In another, add Matcha Powder (1 tablespoon). Leave one as is.
To each bowl, start the macaronage process by folding and scraping the top with a spatula until you get a molten-like mixture that drips down like a ribbon when lifted.
Transfer the batters to piping bags. Pipe out your desired shapes. After piping, knock the bottom of the tray against a flat surface to get rid of air bubbles.
Let the shells dry for approximately 30 minutes in an air-conditioned room. You should be able to touch them gently with the tip of your finger without them sticking.
Bake in a preheated oven at 300 degrees F (150 degrees C) for approximately 10-13 minutes. Let them cool.
To make the filling, place Canned Pumpkin Purée (50 gram), Ground Cinnamon (1/2 teaspoon), Ground Ginger (1/4 teaspoon), Ground Nutmeg (1/4 teaspoon), Ground Cloves (1/4 teaspoon), White Couverture Chocolate Chips (80 gram), and Milk (40 milliliter) in a bowl that is safe for heating.
Simmer some water in a small pot and place the bowl above it. Let the steam melt the chocolate and mix it occasionally until everything is well combined.
Let ganache cool before transferring it to a piping bag and piping onto macaron shells. Decorate with Royal Icing (to taste).