Butter or spray with non stick spray a 10 inch/ 25cm tart tin with a removable base. Preheat oven to 350°F/180°C
Crust
Beat butter and sugar together until combined. Add egg yolk and beat in thoroughly. Stir in flour until it form a soft dough. Don't over mix.
Roll out the dough between two sheets of non stick baking paper that has been floured. While rolling check that the dough isn't sticking. If so, sprinkle with extra flour.
The dough should be a about 1/4inch or 6mm thickness. Check that the dough is rolled out large enough by holding your tart pan over the rolled-out round of dough; the dough should be an inch wider on all sides.
Roll the pastry gently around the rolling pin pulling away the bottom sheet of parchment as you go. Lift and unroll into the pan. Pull up the pastry around the sides and encourage it to fall into the corners. Remove the parchment paper on top. Patch tears with excess pastry. Trim the edges level to the top of the pan.
If you have time chill for 30 minutes.
Filling
Beat butter and sugars until well combined.
Add in eggs, ground almonds and flour. Beat to combine.
Stir in melted chocolate and Amaretto liqueur (if using).
Spoon into pastry case and smooth out the top. Set aside in the fridge while you prepare the pears.
Pears
Peel pears. Cut in half length ways and scoop out the core. Turn the halves onto their cut side and use a sharp knife to cut parallel the long way down the pear leaving a small amount attached at the tip. Make the slices quite thin that way they will cook through. Repeat with remaining pear halves.
Fan out the pears and arrange on the tart. Press down lightly into the filling.
Bake the tart for 45 minutes or until firm and the pastry is golden brown.
Allow to cool. Dust with powdered sugar to serve.
The tart filling will be gooey. If you prefer a firm filling, chill before serving.
Notes
Tips for success
Butter should be a room temperature so that it combines easily with the sugar for both the crust and the filling.
For the crust, take care not to overbeat the butter and sugar.
Stir the flour in gently so as not to toughen the crust dough.
Check all my tips in the post above for how to fan pears.
Instead of fanned pears, arrange thin pear slices in a concentric circle on top of the filling.