In a bowl, place 4 tablespoons of flour, half of the sweetener (reserve the rest for the filling), chilled and chopped butter, a pinch of salt, and a little cold water (about 1-2 tablespoons). Knead the dough by hand for about 5-10 minutes, until it becomes uniform and compact. Add a little more water if necessary.

Form the dough into a ball, wrap it in cling film, and chill in the refrigerator for a while. Meanwhile, prepare the filling.

Wash the apple and cut it into quarters. Peel the skin off and remove the core. Cut each quarter lengthwise in half, then slice into relatively thin pieces. In a bowl, mix the apple pieces with the remaining sweetener and lemon juice. Set aside for a moment.

Then drain the accumulated juice and add the rest of the flour. Mix thoroughly.

Roll out the chilled dough on baking paper and form it into a medium-thick round cake. Spread the apple filling on the dough, leaving a few centimeters from the edge to fold the dough over the filling. Then fold the edges of the dough over the filling. Transfer the cake on the baking paper to a baking sheet. Bake in an oven preheated to 190°C for about 25-35 minutes until the filling and dough are lightly browned. You may reduce the temperature to 170°C halfway through baking.

Enjoy warm or cold.