Dazzle them all at your holiday dessert table with this ethereal French meringue confection.
Preheat oven to 200 degrees with racks in upper and lower thirds. Rub nuts in a towel to remove skins. Coarsely chop nuts; transfer to a sieve, and shake over a paper towel (if desired, reserve dust for garnish); set aside. Draw three 8-inch rounds on parchment paper; place, marked sides down, on 2 baking sheets.
Stir together nuts and confectioners' sugar in a small bowl; set aside.
Put egg whites, granulated sugar, salt, and cream of tartar in the heatproof bowl of an electric mixer; set bowl over a pan of simmering water. Whisk until sugar is dissolved and whites are warm to the touch, about 3 minutes. Transfer bowl to electric mixer fitted with the whisk. Beat on medium speed, increasing to high when soft peaks form; continue until stiff, glossy peaks form.
Gently fold pistachio mixture into egg-white mixture. Spread one-third of the meringue onto each parchment circle (do not smooth tops).
Bake meringues 1 hour. Switch positions of sheets; reduce temperature to 175 degrees. Bake, switching positions of sheets after 45 minutes, until meringues are dry and crisp and can be lifted easily from parchment, 1 to 2 hours. Turn off oven; let meringues cool in oven 45 minutes. Remove, and let cool completely on sheets.
Process 2/3 cup raspberries in a food processor until pureed. Pass through a fine sieve into a bowl; discard seeds. (Puree can be refrigerated up to 1 day.) Beat pastry cream until smooth; set aside. Beat chilled 1/2 cup heavy cream with electric mixer until soft peaks form. Gently fold into pastry cream; set aside.
Set aside a few berries for garnish. Line a baking sheet with parchment paper. Put one meringue on sheet; spread half of pastry cream on top. Spoon 4 1/2 teaspoons puree in a spiral over pastry cream; swirl with a knife. Top with another meringue. Scatter remaining 1 1/3 cups berries over meringue; spread remaining pastry cream on top, leaving a 1 1/2-inch border. Spoon remaining puree in a spiral over pastry cream; swirl with a knife. Top with last meringue; gently press to spread filling to edges. Freeze until filling is solid but not completely frozen, 2 to 3 hours.
Beat remaining heavy cream with electric mixer until soft peaks form. Top dacquoise with whipped cream; garnish with reserved berries, and pistachio dust if desired. Use a serrated knife to cut into wedges; wipe blade clean between cuts.
Store meringue in airtight containers, up to 1 day. Assemble and freeze the dacquoise before dinner -- it'll be ready for dessert.