Combine the flour, powdered sugar, and cold cubed butter in a food processor, pulsing until the mixture resembles fine breadcrumbs. Add the egg yolk and cold water, pulsing just until the dough comes together into a ball.

Wrap the pastry dough tightly in plastic wrap, flatten it into a disc, and chill in the refrigerator for at least 30 minutes to firm up.

In a medium bowl, cream the softened butter and granulated sugar together with a hand mixer until pale and fluffy. Beat in the eggs one at a time, then fold in the almond flour and almond extract until a smooth paste forms.

Preheat your oven to 350°F (175°C). Roll out the chilled pastry dough on a lightly floured surface and cut out circles to fit eight 3-inch tartlet tins, pressing the dough gently into the bottom and sides of each tin.

Spoon 1 teaspoon of raspberry jam into the bottom of each pastry-lined tin, then top with the almond filling, smoothing the surface so it is level with the pastry edge.

Bake for 20 to 25 minutes until the pastry is golden brown and the almond filling is puffed and set. Transfer the tartlets to a wire rack and let them cool completely in their tins.

In a small bowl, whisk the powdered sugar and lemon juice together to form a thick, smooth glaze. Spread a thin layer of glaze over each cooled tartlet, let it set for 10 minutes, and serve alongside a warm cup of coffee.