Preheat the oven to 375 F (190 C) for about 20-30 minutes before baking the cookies. Line a large baking sheet with parchment paper.
In a small bowl, melt the butter and cool in the fridge for about 15 minutes.
1 cup (226 g) unsalted butter, melted and cooled
In another bowl whisk together the flour, cornstarch, baking powder, baking soda and salt until well combined.
2½ cups (300 g) all purpose flour, 1 teaspoon cornstarch , 1 teaspoon baking powder, ¼ teaspoon baking soda, ½ teaspoon salt
In a large mixing bowl, whisk the cooled melted butter, granulated sugar and light brown sugar until well combined. Whisk in the egg, egg yolk and vanilla extract until smooth and well combined.
¾ cup (150 g) light brown sugar, ¾ cup (150 g) granulated sugar, 1 large egg, room temperature, 1 large egg yolk, room temperature, 2 teaspoons (10 ml) vanilla extract
Stir the dry ingredients into the wet, followed by the white chocolate chips until just combined. Gently stir half of the raspberries until combined. Reserve some for topping the cookies right before baking.
1 cup (170 g) white chocolate chips or chunks, ½ cup raspberries, cleaned and dried
Using a medium cookie scoop (2 tablespoons, 30 ml), scoop the cookie dough into balls. Roll the cookie dough into sugar and place onto the lined baking sheet about 3 inches ( 8 cm) apart. Top with 1 - 2 raspberries if you like. Bake at 375 F (190 C) for 10 -12 minutes or until the edges of the cookies are set and are a light golden brown. Cool the chewy raspberry cookies on the baking sheet for 3 - 4 minutes. While the cookies are cooling, top them with more white chocolate chips if you like. Then transfer to a cooling rack to cool completely to room temperature and enjoy!