1) Preheat the oven to 350°F. Lightly grease an 8" round cake pan that's at least 2" deep. If your 8" round pan is shallower than 2", use an 8" square pan, or 9" round pan.
2) Beat together the eggs and sugar until smooth.
3) Add the butter, cottage cheese or ricotta, sour cream, and flavor/extract, beating until well combined.
4) Add the flour, salt, and baking powder, stirring or beating gently to combine.
5) Pour the batter into the pan, and scatter the berries evenly over the top.
6) Bake the cake for about 50 minutes, until a tester inserted into the center comes out clean.
7) Remove the casserole/cake from the oven, and sprinkle the top heavily with cinnamon-sugar, if desired. Let it rest at room temperature for 30 minutes, to firm.
8) Serve warm, in wedges, squares, or rounds cut with a biscuit cutter.
Yield: 8 to 10 servings.