Strawberry Swirled Cupcakes with Strawberry Frosting

Ingredients

• 12 purchased shortbread cookies, such as Lorna Doone
• 1 Tbsp. butter, melted
• 1 1/2 Teaspoons granulated sugar
• 1/2 Cup (1 stick) unsalted butter, at room temperature
• 2 Cups confectioners' sugar
• 1 Tbsp. whole milk
• 1 Package (16 ounces) Driscoll's strawberries, divided
• 1 1/2 Teaspoons cornstarch
• 6 Tablespoons unsalted butter, at room temperature
• 2/3 Cup granulated sugar
• 1 large egg, at room temperature
• 1 Cup cake flour
• 1 Tsp. baking powder
• 1 Tsp. salt
• 1/3 Cup whole milk
• 1 Tsp. vanilla