In a large bowl, mix together mayonnaise, wasabi paste, and crabmeat. Gently fold in caviar. Season with salt and pepper; refrigerate until ready to serve. To serve, fill pastry shells with crab-caviar mixture; garnish with more caviar.
Heat oven to 400 degrees F. Defrost pastry dough, following label directions. In a small bowl, whisk together egg and milk; set aside. Line 2 baking sheets with parchment; set aside. On a lightly floured surface, cut pastry with a 1-inch pastry cutter to make 36 rounds. Use the cutter to make indentations on the centers of the rounds without cutting through the dough. Using a pastry brush, coat rounds with egg wash. Cook on prepared baking sheets until raised and golden brown, 10 to 12 minutes. Transfer to a wire rack to cool. Gently push the indented center into the cavity, and remove to form a shell. If necessary, use a paring knife to coax out the center. Level the bottom with a paring knife so that the shell won't wobble. Repeat with remaining shells. Yield: 3 dozen shells
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