Gently fold together raspberries, crystallized ginger, confectioner's sugar and liqueur, if using, together. Crush a few raspberries to give off their juices. Cover and let stand 1 hour.

Preheat oven to 425° F.

Sift all-purpose flour, cake flour, 1/3 cup sugar, baking powder, nutmeg, salt and baking soda together into large bowl. Add butter and cut in with pastry blender until mixture resembles coarse crumbs with pea-sized pieces. Stir in enough buttermilk to make a shaggy dough. Turn out onto a lightly floured work surface and knead a few times just until dough comes together.

With floured hands, pat out to a 12-by-6-inch rectangle about 3/4-inch thickness. Using a large sharp knife, cut into 8 (3-inch) squares. Transfer to an unlined baking sheet. Brush tops lightly with 2 teaspoons cream and sprinkle with the remaining 1 tsp. sugar.

Bake until risen and golden brown, about 20 minutes.

Whip remaining cream, confectioners' sugar and vanilla in a chilled medium bowl with an electric mixer set on high speed until soft peaks form. (The whipped cream can be covered and refrigerated up to 8 hours ahead. Whisk briefly before serving.)

For each serving, cut shortcake in half using a serrated knife. Top bottom half with some raspberries and their juices, followed by a dollop of whipped cream and then top half of shortcake. Garnish with a mint sprig and serve immediately.