Bring pears, sugar, water and lemon juice up to a simmer. Cook pear just below a simmer (and place a plate or piece of parchment over surface of liquid to keep pears from floating) until tender, about 10 minutes. Remove from heat. After pears have cooled a bit, remove from liquid, sprinkle with brandy, toss and chill until ready to serve.
To prepare crust, cream butter and sugar together. Stir in egg yolks, adding one at a time. Sift together flour, cocoa and salt and add to butter mixture. Mix until dough just comes together. Shape in to a disc and chill until ready to roll. If preparing ahead of time, pull dough from fridge an hour before rolling.
On a lightly floured surface, roll out dough to just over ¼-inch (.5 cm) thick. Line a 9-inch (23 cm) removable-bottom tart shell with dough, trim edges and chill for 20 minutes.
Preheat oven to 350 F (180 C). Dock pastry with a fork and bake for 18-20 minutes. Allow to cool.
Reduce oven temperature to 325 F (160 C). Place chopped chocolate in a large bowl. Heat cream with spices to just below a simmer and pour over chocolate. Let it sit for a minute, then stir slowly. Stir in vanilla extract.
Whisk egg in a small cup then stir into chocolate. Pour into chocolate shell and bake for 12 minutes. Let cool for 15 minutes, then chill for 2 hours before serving.
To garnish with pears, slice, pears thinly and arrange over tart.