Preheat the Oven: Preheat your oven to 180°C (350°F).

Prepare the Filling: In a bowl, mix the cottage cheese, powdered sugar, and 1 egg until smooth. Set aside.

Prepare the Batter: In a large bowl, beat the 4 eggs with a pinch of salt.

Add the sugar and continue to beat until the mixture is light and fluffy.

Gradually add the vegetable oil and kefir, mixing well.

Sift the flour and baking powder into the wet ingredients and mix until just combined.

Assemble the Pie: Pour half of the batter into a greased or lined baking dish with a diameter of 20-30 cm (8-12 inches).

Evenly spread the cottage cheese filling over the batter.

Pour the remaining batter over the filling, spreading it evenly.

Bake: Bake in the preheated oven for 45 minutes, or until the pie is golden brown and a toothpick inserted into the center comes out clean.

Cool and Serve: Allow the pie to cool slightly before serving.