Beat 4 egg yolks and 1/2 cup sugar in a mixing bowl until light and pale, about 3 minutes. In a double boiler, heat 1 cup heavy cream until warm, then slowly pour over egg mixture, stirring until thickened, about 5 minutes. Mix in 8 oz chopped white chocolate until melted and smooth. Allow to cool.

Preheat oven to 190ºC (374ºF). In a food processor, combine 1 1/2 cups flour, a pinch of salt, 1/4 teaspoon cayenne, and 1 teaspoon cinnamon; pulse until mixed. Add 1/2 cup cubed butter, and process until crumbly. Add 1/4 cup sugar, 1 egg, and 1 extra yolk, pulsing until cohesive.

Wrap the dough in parchment paper and refrigerate for at least 1 hour. Roll out on a floured surface until 1/8 inch thick. Cut shapes for tartlet tins.

Preheat oven to 190ºC (374ºF). Line tartlet shells with parchment and pie weights, bake for 10 minutes. Remove weights, bake for another 5 minutes until golden brown, then cool completely.

Spoon mousse into cooled tartlet shells, smoothing tops with a spatula. Refrigerate for at least 2 hours before serving. Optionally garnish with fresh fruit or dust with cinnamon and icing sugar.