• Preheat oven to 425° degrees. Line a baking sheet with parchment paper, then set the baking sheet aside and place the parchment paper on a flat surface.
• Make the cinnamon sugar: In a small bowl, combine ¼ teaspoon cinnamon with ¼ cup sugar; set aside. 
• If using store-bought pie crust, thaw refrigerated pie dough according to package instructions. Roll out homemade dough or storebought dough into a 9-inch round circle.
• In a large bowl, stir together blueberries, raspberries, strawberries, cornstarch, lemon zest and juice, and remaining 1 tsp cinnamon and ½ cup sugar until the fruit is well coated. 
• Spoon the berry mixture onto the center of the dough round.
• Gently fold dough over part of the berry mixture, and then continue around the circle to create pleats.
• Place butter cubes on top of the berry mixture, a few inches apart.
• Use a pastry brush to lightly glaze the tops of each dough with the egg wash.
• Sprinkle the prepared cinnamon sugar mixture evenly over both of the galettes. 
• Optional: sprinkle a little sanding sugar around the crust for additional sweet texture.
• Bake at 425° degrees for 20-25 minutes, just until the tops of the dough become lightly golden. Cool on a baking rack for 5-10 minutes.

Make the white chocolate stars

• In a medium microwave-safe bowl, melt the white chocolate in 30 second increments and whisk until chocolate has melted.
• Use a small icing spatula to spread the melted chocolate over a sheet of parchment paper. Place on top of a plate and freeze for 5 minutes.
• When the chocolate has firmed up but is not yet frozen, use a star cutter to cut out star shapes. Set the shapes onto a plate and refrigerate or freeze until you are ready to decorate the galette.