In a large mixing bowl or a bowl of a stand mixer, combine the cream cheese and butter. Whip them together until they become light and fluffy (2-3 minutes).

Gradually add the all-purpose flour to the bowl. Pour one cup at a time and mix well after each addition to ensure a smooth dough.

Once the dough is well-mixed, wrap it in plastic and let it rest in the refrigerator. It should chill for at least one hour to firm up.

Preheat your oven to 350°F (180°C) and line a cookie sheet with parchment paper or silicone baking mat.

After the dough has chilled, roll it out on a silicone mat or a clean surface. Sprinkle powdered sugar to prevent sticking, not flour. Roll the dough to about ¼ inch thickness.

Cut the dough into 2-inch squares. Place a small dollop of your chosen filling, about ½ to 1 teaspoon, in the center of each square.

To shape the kolaczki, overlap opposite corners of the dough square towards the center over the filling, pressing the dough together lightly to seal. Brush a tiny bit of water or beaten egg white on one point to help seal the opposite point on it.

Carefully transfer the filled cookies to a parchment paper-lined baking sheet using a spatula.

Once baked, remove the kolaczki from the oven. Use a spatula to transfer the cookies to a wire rack and allow them to cool completely.