Puff-Pastry Plum and Thyme Galette

Ingredients

• Cooking spray, as needed
• 1 sheet frozen puff pastry, thawed overnight in the refrigerator
• 8 plums, halved
• 2 tablespoons honey, plus more for finishing
• 1 teaspoon pure vanilla extract
• ⅓ cup sugar
• ¼ cup plus 2 tablespoons cornstarch
• Pinch of salt
• 1 tablespoon thyme leaves, plus sprigs for garnishing
• 1 large egg
• 2 tablespoons turbinado sugar
• Ice cream or whipped cream, for serving