Place flour, confectioners sugar, and pistachio nut meats into the bowl of a food processor and process until nuts are finely ground, like sand. Cut butter into 16 pieces and add to the processor; pulse ten times.

Place the egg yolk in a 1/4 cup measure, break it up with a fork, and add ice water to fill the measure. Add the water and egg yolk to the food processor and pulse 10 to 12 long pulses or until the dough comes together. The dough will be very sticky. Wrap the dough in plastic or wax paper and chill for 30 minutes.

Preheat oven to 350°F. Divide chilled dough into four pieces, and place one in each tart pan. Flour your fingers, if necessary, and press the dough evenly into the mold across the bottom and sides. You can flatten the bottoms with a glass dipped in flour for uniform thickness.

Chill for 10 minutes. Line each tart pan with foil, and place on a baking sheet. Fill each shell with pie weights or dried beans, and bake for 10 minutes; remove the foil and weights and bake an additional 5 minutes. Remove from the oven and immediately brush the bottoms and sides of the hot shells with egg white and let cool.

Add the cream and sugar to the saucepan and continue cooking while stirring for 3-5 minutes.

Once the sugar is dissolved, turn off the heat. Stir in the saffron and rosewater and set aside to cool a bit.

Bring the tarts to room temperature about 15-30 minutes before serving. Garnish with pistachios.