1. Put 6 egg yolks and sugar into the bowl of an electric mixer fitted with the whisk attachment. Beat on high speed until thick and pale yellow, and a ribbon forms when beaters are lifted, about 5 minutes. Add flour; beat until combined.

2. Meanwhile, bring milk, vanilla, and nutmeg to a boil in a 2-quart stainless-steel saucepan over medium-high heat. With mixer running, pour about one-quarter milk mixture into egg mixture. Slowly add egg-milk mixture to saucepan with remaining milk. Reduce heat to medium. Cook, whisking constantly, until mixture thickens and bubbles in center, 4 to 5 minutes. Pour through sieve into a medium bowl. To prevent a skin from forming, press plastic wrap directly onto surface of custard. Let cool, 30 to 45 minutes. When cool, refrigerate until chilled and set, at least 2 hours.

3. On a lightly floured surface, roll out dough to 1/8 inch thick. Cut into eight 6-inch squares. Place squares into ovenproof ceramic cups, allowing excess to drape 1 to 1 1/2 inches over edges. Repeat with remaining cups.

4. Mix remaining egg yolk and 1 tablespoon cream in a small bowl; brush over surface of dough, and refrigerate, at least 1 hour.

5. Heat oven to 350 degrees. Place cups on a baking sheet, and gently prick bottom of dough inside of cups several times with the tines of a fork. Bake until crust is a deep golden color and inside of pastry shell is dry, 20 to 25 minutes. Let cool completely on a wire rack.

6. Meanwhile, chill bowl and whisk attachment of an electric mixer. Whip remaining cup cream on medium-high speed. When cream starts to thicken, add confectioners' sugar, and beat until soft peaks form. Add rum, and continue to whip until soft peaks form.

7. Spoon 1/4 cup chilled custard into each cooled pastry shell. Add a dollop of whipped cream, and serve.