Preheat oven: Set to 350°F (177°C). Line two baking sheets with parchment paper or silicone mats.

Make dough: Using a stand mixer fitted with the paddle attachment, beat butter, powdered sugar, vanilla, peppermint extract, and salt until smooth and creamy.

Add flour: Mix in flour gradually in three portions on low speed. If dough feels crumbly, add 1 tbsp cold water until it comes together.

Shape cookies: Roll dough into 2‑teaspoon balls and place 1 inch apart on baking sheets.

Bake and indent: Bake 10 minutes, remove from oven, and press a small indentation in each cookie’s center using your thumb or a small spoon. Return to oven for 7–9 more minutes until edges are firm but cookies remain pale.

Cool: Reinforce indentations gently after baking, then let cookies cool 5 minutes on sheet before transferring to a wire rack.

Make chocolate filling: In a small saucepan, melt chocolate, butter, and corn syrup over low heat, stirring until smooth. Let cool slightly (about 5 minutes).

Fill and decorate: Spoon chocolate into the cookie centers and sprinkle crushed peppermint candies on top while chocolate is still soft. Allow to set before storing.