Mix the quark, cottage cheese, lemon juice and milk and stir until creamy. Add the thawed or fresh berries and the apple cubes and mix with the oat flakes. Add a good pinch of cinnamon, depending on your taste.
I think the quark breakfast is very tasty if you add a teaspoon of core mixture over it (it is usually made for salads).
Breakfast provides all the important nutrients. A lot of protein, good carbohydrates and little but good fat (through the kernels and nuts). The cinnamon gives a delicious note and so everything tastes really delicious even without sugar.