01 - Preheat oven to 325°F and line two baking sheets with parchment paper.
02 - In a large bowl, beat softened butter and powdered sugar until light and fluffy.
03 - Mix in vanilla extract until fully incorporated.
04 - Whisk together flour, cornstarch, and salt in a separate bowl.
05 - Gradually add dry ingredients to butter mixture, mixing until soft dough forms.
06 - Lightly flour work surface and roll dough to 1/4-inch thickness. Cut with round or flower-shaped cookie cutter.
07 - Transfer cookies to baking sheets. Gently press edible flower onto each cookie, brush lightly with egg white to adhere, and sprinkle with sugar if desired.
08 - Bake for 12-15 minutes until edges are barely golden.
09 - Let cookies rest on baking sheets for 5 minutes, then transfer to wire rack to cool completely.