You will need sufficient pastry for a deep 1-crust 9 inch pie (1 L).
Line a pie shell with the pastry. Preheat oven to 425°F.
TO MAKE THE FILLING: Measure the blueberries into a medium bowl. Combine the sugar, flour, salt and lemon rind, toss with the berries and pour into the pie shell. Sprinkle on the lemon juice. Arrange the berries evenly.
Line the edges of the pastry with strips of aluminum foil to keep them from browning too fast. Bake for 15 minutes, then reduce heat to 350°F and bake for another 15 minutes.
While the pie is baking, prepare the custard by beating the yolks and sugar together, then mixing in the cream. Spoon the custard gently over the berries in the baked pie. Grate a light film of nutmeg over the top.
Continue baking at 350°F for 20 to 35 minutes. The custard is ready when the tip of a knife inserted into it comes out clean. Cool and serve freshly made. Yields 6 servings.