Prepare the Snowskin Dough: In a bowl, combine glutinous rice flour, powdered sugar, and matcha powder. Gradually add cold water and melted shortening, mixing until a smooth, non-sticky dough forms. Divide the dough into desired portions (e.g., 25-30g each), cover with plastic wrap, and chill for 30 minutes.

Prepare the Custard Filling: In a saucepan, whisk together custard powder, granulated sugar, and milk until smooth. Cook over medium-low heat, stirring constantly, until the mixture thickens to a pudding-like consistency. Remove from heat and stir in the cold, diced butter until fully incorporated and melted. Let the custard cool completely, then fold in the diced fresh strawberries. Chill the filling until firm enough to handle, then divide into portions (e.g., 20-25g each).

Assemble the Mooncakes: Lightly dust your mooncake mold with cooked glutinous rice flour. Take one portion of chilled snowskin dough, flatten it into a thin disk, and place a portion of the custard-strawberry filling in the center. Gently bring the edges of the dough up and seal completely around the filling, forming a ball. Place the filled ball into the mooncake mold and press firmly to create the pattern. Carefully release the mooncake from the mold.

Chill and Serve: Arrange the finished mooncakes on a plate or in an airtight container. Refrigerate for at least 1-2 hours before serving to allow them to firm up. Enjoy these refreshing snowskin mooncakes chilled!