A that recipes with  hazelnut is given of my grandma.
For healing use bark,leafs,like bark use a early spring in juice time,and leafs use in blooming,keeping in wood box 2 years.

In medicine is used all the aboveground part of the tricolor of violet and violet field collected at the beginning of flowering. Most often recommend to behold with acute respiratory diseases, chronic bronchitis: Violet promotes liquefaction and sputum. In addition, it is used in inflammatory diseases of the kidneys and urinary tract infections, and allergic dermatitis; diathesis.