Combine the flour, confectioners' sugar, and salt in a large mixing bowl. Add the butter, and mix with a pastry blender, a fork, or your fingers until the mixture resembles coarse crumbs.

Whisk the egg yolk in a small bowl, and then add it to the flour mixture. Gently combine until the dough begins to come together. If the dough is too dry, add a small amount of water at a time until it comes together. The dough should be moist but not sticky.

Transfer the dough to a lightly floured surface, and shape it into a disk. Wrap in plastic wrap, and refrigerate for at least 30 minutes. 

Peel, core, and slice the pears to about 1/4-inch thickness. Toss the sliced pears with lemon juice to keep them from browning.

Using an electric mixer on medium speed, beat the butter and sugar until light and fluffy. Then, mix in the almond flour.

Add the eggs one at a time, and then mix in the almond extract and flour. The mixture should be smooth and creamy.

Spread the filling evenly over the chilled crust.

Arrange the sliced pears on top of the filling, overlapping slightly and leaving some of the filling visible. If you like, scatter a handful of sliced almonds over the top of the tart.

Place the tart pan on a lined rimmed baking sheet to catch any potential spills. Bake 35 to 45 minutes, or until the filling is browned and set, and the pears are tender.

Allow the tart to cool before serving. Serve warm or at room temperature.