Place the freeze-dried raspberries in between parchment paper (or plastic bag) and crush them with a rolling pin. (Alternatively, you can use a small food processor and pulse until powder.)
1/3 cup freeze dried raspberries
Sift the crush raspberries through a fine mesh sieve and discard the seeds and large bits.
In a mixing bowl with a paddle attachment, mix the prepared raspberry powder, flour, sugars, cornstarch, baking powder, and salt.
3 cups all-purpose flour, ½ cup granulated sugar, ¼ cup packed brown sugar, ½ teaspoon baking powder, ¼ teaspoon coarse kosher salt, 1 tablespoon cornstarch
Add butter and mix on low speed until the mixture is evenly moistened, 1-2 minutes. The mixture should resemble wet sand.
1 ½ sticks unsalted butter
Add egg and vanilla extract and mix until just combined, about 30 seconds. The dough will be crumbly, but it should stick together when you squeeze it in your hand.
1 large egg, 2 teaspoons pure vanilla extract
Divide the dough into 2 equal parts. Knead it into a smooth ball. Place each dough ball between 2 parchment sheets and roll it out into ¼-inch-thick disc. (TIP: Place a silicone mat under the parchment paper to roll it out, so it stays in place. And this adjustable rolling pin is nice for rolling out even dough.)
At this point, you can move on to shaping and baking the cookies right away. Or you can put the dough into plastic bags and refrigerate for up to 3 days or freeze for up to 3 months.