For the cookies:
- 1 3/4 cups all-purpose flour
- 1 teaspoon baking soda
- 1/2 teaspoon salt
- 1 1/4 sticks (10 tablespoons) unsalted butter softened
- 1 1/2 cups plus 2 teaspoons sugar
- 1 large egg
- 2 teaspoons pure vanilla extract
- 1 vanilla bean halved lengthwise, seeds scraped and reserved
For the filling:
- 1 1/3 cups fresh raspberries (1/2 pint)
- 7 1/2 ounces best-quality white chocolate, coarsely chopped
- 1/3 cup heavy cream
Preheat oven to 350 degrees. Whisk together flour, baking soda, and salt; set aside.
Mix butter and 1 1/2 cups sugar with an electric mixer on medium-high speed until pale and fluffy, 2 to 3 minutes. Add egg, extract, and vanilla seeds; mix until smooth. Reduce speed to low. Gradually mix in flour mixture. Scoop batter using a 1-inch ice cream scoop; space 2 inches apart on baking sheets lined with parchment paper.
Bake, rotating sheets halfway through until golden and just set, 8-10 minutes. Let cool on parchment on wire racks.
Puree raspberries and remaining 2 teaspoons sugar in a food processor. Pour mixture through a fine sieve into a small bowl, pressing to extract juice; discard seeds. Set mixture aside. Melt white chocolate in a heatproof bowl set over a pan of simmering water. Remove from heat; whisk in cream in a slow stream. Slowly whisk in reserved raspberry mixture. Refrigerate up to 45 minutes.
Spread 1 heaping teaspoon raspberry cream on the undersides of half the cookies. Sandwich with remaining cookies.