In a saucepan set over medium heat, cook the ¼ cup granulated sugar and 1 cup of raspberries, stirring constantly, until they are broken down and syrupy, about 10 minutes.

Set a mesh colander over a bowl. Pour the raspberry liquid through the strainer and set aside to let cool.

Measure out ½ cup frozen raspberries, rough chop into small pieces, and place in a freezer safe bowl.

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

In a small bowl, mix together the remaining cornstarch with water until thin and watery.

In a large bowl of an electric mixer, beat the unsalted butter and 1 ¼ cups of sugar until soft and creamy.

Slowly beat in the cornstarch water mixture, milk, and cooled raspberry liquid into the creamed butter and sugar.

Slowly beat in the flour mixture until just combined. Add food coloring if desired.

Fold in the chopped raspberries gently.

Keep the dough in the bowl, cover, and freeze for at least 1 hour.

Preheat the oven to 325°F and line a baking sheet with parchment paper.

Using a large cookie scoop, make dough balls, roll in the extra sugar, and place on baking sheet.

Bake at 325°F for 15 minutes and reshape cookies after baking as needed.