Preheat oven to 350F
Cut the brain in half length-wise and dip it into the mixture of flour, salt and pepper.
In a very hot saucepan, add 50 g of butter. When the butter stops sizzling, brown the two parts of the brain. Coat regularly with butter. Cook in the oven at 350°F for about 5 minutes.
Take out of the oven and set the brains aside.
Add the rest of the butter (100 g) to the saucepan and cook over low heat until it browns and starts smelling like hazelnut. Add a dash of lemon juice to stop the cooking, and add parsley. Adjust the seasoning.
Coat the brains with the brown butter and serve.