Unless your fava beans are small and young, their waxy skin needs to be removed. To do this, bring the stock to a boil in a medium saucepan. Drop in the shelled beans and cook for 5 minutes (6 if the beans are frozen). Drain and drop into a bowl of ice-cold water to stop the cooking. Cut a tiny slit in the outer skin of each bean with your thumbnail, and pinch the skin to slip it off- you will get more dexterous as you go. (The beans can be prepared up to 2 days in advance and refrigerated in an airtight container).
Preheat the oven to 425 degrees F. Grease a 9-inch round cake pan with olive oil and line the bottom with parchment paper.
In a large mixing bowl, whisk together the eggs, cream, cheese and mint. Season with salt, a few gratings of nutmeg, and a few turns of the pepper mill. Add the beans, stir gently to combine, and pour into the prepared cake pan.
Put into the oven to bake for 25 minutes, until golden and puffy. Transfer he pan on a rack to cool for 5 minutes- the top will settle. Remove from the pan and serve warm or at room temperature, with a salad of mixed greens. This will keep for up to a day, tightly wrapped and refrigerated.