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
6 ounces (1 cup) fresh raspberries
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 cookies 4 minutes. Remove from oven; gently tap baking sheets on counter to flatten cookies. Return to oven, switching positions of sheets; bake until cookies are just set, 4 to 6 minutes more. 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. Whisk in reserved raspberry mixture. Refrigerate 30 minutes.
Spread 1 heaping teaspoon raspberry cream on the undersides of half the cookies. Sandwich with remaining cookies. Cookies can be stored at room temperature in an airtight container up to 2 days.