Preheat oven to 350* F. Butter a 13" x 9" baking dish; set aside.
In a blender or food processor, mix butter, sugar, eggs, sour cream, orange juice, flour and baking powder until blended. Pour half the batter into prepared baking dish.
In a food processor prepare blintz filling. Combine cream cheese, cottage cheese, egg yolks, sugar and vanilla extract. Mix until smooth. Drop filling by heaping spoonfuls over batter in baking dish. With a knife, spread filling evenly; it will mix slightly with batter. Pour remaining batter over filling.
Unbaked souffle may be covered and refrigerated several hours or overnight until ready to use.
Before baking, bring souffle to room temperature. Bake uncovered 50 to 60 minutes or until puffed and golden.
Serve immediately with sour cream and Blueberry Syrup or assorted jams.