In a small saucepan over medium heat, combine frozen raspberries and granulated sugar.

Stir until the raspberries break down and the mixture reaches a smooth, glossy consistency, then remove from heat and cool.

Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a bowl, whisk together gluten-free flour, cornstarch, baking powder, and kosher salt.

In a separate bowl, cream together the unsalted butter and remaining sugar until light and fluffy.

Mix in the cornstarch-water mixture, milk, raspberry syrup, and food coloring until combined.

Gradually incorporate the dry mixture into the wet ingredients, stirring until the dough forms.

Fold in chopped frozen raspberries carefully.

Using a cookie scoop, drop dough onto prepared baking sheets, leaving space between each scoop.

Bake for 12-15 minutes, until edges are golden and the aroma fills the kitchen.

Allow cookies to cool slightly on baking sheets before transferring to wire racks.