Finely grind 1/3 cup pistachios with sugar, coriander, and cardamom in a food processor. Finely chop remaining pistachios and reserve.
Put stack of phyllo sheets on a work surface and cover with 2 overlapping sheets of plastic wrap and a dampened kitchen towel. Put 1 phyllo sheet on a cutting board and brush with some butter.
Sprinkle phyllo sheet evenly with half of nut sugar, then top with another sheet of phyllo.
Brush phyllo with some butter and sprinkle with remaining nut sugar. Top with remaining phyllo sheet, pressing down gently, then brush with remaining butter. Chill phyllo 10 minutes.
Trim edges of phyllo with a sharp knife to make 1 (15- by 12-inch) rectangle.
Cut stack lengthwise to make 4 (3-inch-wide) strips, then cut strips crosswise into 5 (3-inch) squares, forming 20 total. Halve each square diagonally, then carefully transfer triangles, 1 at a time, with a spatula onto a parchment-lined large baking sheet, spacing them 1/4inch apart. Cover triangles with another piece of parchment and a baking sheet (as a weight).
Bake in lower third of oven until golden, 15 to 18 minutes.
Remove top baking sheet and carefully peel off top parchment (some phyllo may stick to it), then cool crisps on baking sheet on a rack.
Beat cream in a bowl with an electric mixer until it holds soft peaks, then gently fold in lemon curd.
Put 1 crisp on each of 8 plates. Top each crisp with 1 heaping tablespoon mousse, then layer with another crisp and tablespoon mousse. Top with crisps.
Sprinkle reserved chopped nuts around napoleons.
·Crisps keep in an airtight container at room temperature 1 week.·Mousse can be made 4 hours ahead and chilled, covered.
