Cut the cold butter into small cubes, then work it together with the Czelli all-purpose flour, the salt, the sugar, and the egg in a food processor.

Wrap the dough in plastic wrap, flatten it slightly, then place it in the freezer for 30 minutes.

For the frangipane cream, finely grind the almonds together with the sugar. Add the soft butter, the eggs, the rum, and the bitter almond extract, then work until creamy.

Mix the pitted sour cherries with the brown sugar and cornstarch, so that the fruit's juices thicken slightly during baking.

On a floured surface, roll the chilled dough out to 3–5 mm (⅛–¼ in) thick, then carefully press it into the 28 cm (11 in) pie pan.

Spread the almond frangipane cream evenly over the dough, then arrange the sugared, starch-coated sour cherries on top in a single layer.

Place the pie in an oven preheated to 180 °C (350 °F) and bake for 55–60 minutes. It's done when the almond filling has risen nicely and the sour cherries have softened.

Let the finished pie cool completely in the pan. Only then slice it, so that the frangipane cream and the fruit layer both hold their shape nicely.