Preheat oven to 350°F. Line baking sheets with parchment paper.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a large bowl, use an electric mixer to beat the butter and sugar until light and fluffy, about 2 to 3 minutes. Scrape down the bowl. Add the egg and vanilla, and beat until combined. Gradually beat in the flour mixture.

Place the remaining 2 tablespoons of sugar in a shallow dish. Using a small spring-loaded scoop, divide the dough into balls, then roll in sugar to coat. Place on prepared baking sheets, spacing 2 inches apart. Flatten slightly with your palm.

Bake for about 9-10 minutes, or until the cookies set and just begin to brown at the edges. Cool for 5 minutes before transferring to a wire rack to cool completely.

Grind the freeze-dried raspberries into a fine powder and sift twice to remove seeds.

Melt the white chocolate in a double boiler or microwave. Remove from heat and whisk in the heavy cream until fully combined. Stir in the raspberry powder and let cool to room temperature.

Spread 1 heaping teaspoon of filling on the bottom of half the cookies and top with the remaining cookies to sandwich.

Fill a piping or zip-top bag with melted white chocolate, drizzle over the tops of each sandwich, and sprinkle with crushed raspberries.