For the pastry, beat the butter and icing sugar together until smooth. Push the hard-boiled egg yolk through a sieve and stir the raw egg yolk and vanilla into it. Add this to the butter mixture and stir until blended. Add the flour and salt to the butter mixture and stir until blended. Shape the dough into a disc (it will be very soft), wrap in plastic and chill until firm, about two hours.
On a lightly floured work surface, gently knead the dough just a little soften, then roll it out to a circle about 33 centimeters across and six millimeters thick. Carefully lift this and line a 23 centimeter removable-bottom fluted tart pan, press it into the bottom and sides and trim away any excess dough. Chill the tart shell for 30 minutes.
Preheat the oven to 325 °F (160 °C). Place the chilled tart shell onto a baking tray and dock the bottom of the pastry with a fork. Bake the tart shell for about 20 minutes, until the edges just begin to brown. Cool the tart shell to room temperature.
To fill and bake the tart, preheat the oven to 350 °F. Keep the cooled, baked tart shell on a baking tray.
Gently toss the sliced apple with the Marsala and set aside, stirring occasionally.
Whisk the ricotta, 1/4 cup (50 grams) of the sugar, grated chocolate, egg, egg yolk, lemon zest and nutmeg together. Strain the Marsala from the apples into this ricotta mixture and stir to blend. Pour the ricotta filling into the baked tart shell and arrange the apples nicely overtop. Brush the apples with the melted butter and sprinkle them with the remaining one tablespoon (12 grams) of sugar.
Bake the tart for about 25 minutes, until the apples are tender when pierced with a fork. Cool the tart to room temperature then chill until ready to serve.
The tart will keep, refrigerated for up to two days.