1. Place all ingredients in work bowl of food processor and process until dough starts to come together in a ball. Remove and form into a ball. Chill for at least 1 hour before using.
1. In a saucepan, bring the milk, half of the sugar and vanilla bean to a full boil.
2. In a bowl, beat the yolk with the remaining sugar and then fold in the cornstarch. Dilute this mixture with half of the boiling milk, whisking, then put back into the saucepan and cook the cream until it comes to a full boil, whisking constantly and vigorously.
3. Continue to whisk the cream over the heat for a few seconds, and then add half of the butter. When the butter has been incorporated perfectly, remove from heat and pour into a bowl to cool rapidly.
4. Add the remaining butter, beating vigorously for 4-5 minutes; the cream should increase in volume and become very light.
Preheat oven to 425 Degrees.
Roll out dough and place in a tart pan with a removable bottom. Trim edges. Bake for 10 minutes. Cool completely.
Paint a thin layer of apricot glaze over pastry shell. Fill baked tart shell with pastry cream and top with nectarines. Paint remaining glaze over fruit.