10Special equipment: 12 (1/8-cup) barquette molds or a mini-muffin pan with 12 (1/8-cup) muffin cups preparation.
Put oven rack in upper third of oven and preheat oven to 400°F Brush molds with melted butter and lightly dust with flour, knocking out excess flour.
Stir together flour (3 tablespoons) and salt in a small bowl.
Beat together softened butter and granulated sugar in a bowl with an electric mixer at high speed until pale and fluffy. Beat in almond paste and vanilla until combined well, then beat in egg until combined. Reduce speed to low and add flour mixture, mixing until just combined.
Divide batter among molds or muffin cups, spreading evenly, then transfer to a baking sheet (not necessary if using muffin pan).
Bake cakes until just firm and edges are golden, about 15 minutes. Turn cakes out onto racks and cool completely, about 5 minutes. Turn cakes right side up and dust tops with confectioners sugar just before serving.
Cooks' note: Cakes can be made 1 day ahead and cooled completely, uncovered, then kept in an airtight container at room temperature.