Grapefruit-Vanilla Shortbread

Ingredients

• 1/2 cup (1 stick) unsalted butter, room temperature, cut into pieces, plus more for pan
• 1 tablespoon finely grated grapefruit zest
• 1 teaspoon vanilla extract
• 1/3 cup plus 1 cup powdered sugar
• 1 cup all-purpose flour
• 1/2 teaspoon kosher salt, plus more
• 2 tablespoons fresh grapefruit juice
• Himalayan pink salt, dried hibiscus flowers, red sprinkles or sanding sugar, dried rose petals, and/or cracked pink peppercorns (for serving; optional)
• A 9-inch springform pan