In a food processor, process the almond paste and sugar into fine pieces. Add the butter, egg yolks, and almond extract. Pulse until smooth. Pour into a bowl and add the almonds. Cover and refrigerate for 1 hour.
With the rack in the middle position, preheat the oven to 200 °C (400 °F). Line a 43 X 30-cm (17 X 12-inch) baking sheet with parchment paper.
On a floured work surface, roll out the dough into two 25-cm (10-inch) squares of about 3-mm (1/8-inch) thick. Cut each piece of dough into four squares.
Brush one side of the pastry with the beaten egg. Spoon about 30 ml (2 tablespoons) of the almond mixture in the centre of each square. Close to form triangles. With a fork, press the edges to seal the dough.
Place the turnovers on the baking sheet. With scissors, make a small incision in the centre of the dough of each pastry to allow steam to escape.