Mushroom gratin with mussels and arugula: a summer starter.

El mushroom Gratin is a quick recipe to make, very clean, since we will not almost dirty utensils, with which we can use as a garnish for our main dishes, both fish and meat or as a starter.

Ingredients: mushroom, bechamel and mushroom filling: fried mushroom or duxel and pickled mussels.

STEPS:
The first thing we will do is clean the mushrooms removing the foot or tail from as deep as we can to leave as much space as possible in order to fill it. We wash them with plenty of water to remove any possible dirt.

For the mushroom filling we will make a mushroom or duxel sauce and add the pickled mussels.

We reuse the tails that we have previously removed and, once clean, we cut them as small as possible. Add the same amount of spring onion and pour it into a saucepan with a knob of butter. Then we poach it slowly until the onion is browned.

We fill in the mushrooms and we leave a hole where to place the pickled mussel.

For bechamel we only need:
-100gr of flour
-100gr butter
-1 liter of milk
-Nutmeg, 1 c / s
-salt, 1c / s

To elaborate this bechamel We will put the flour and butter in a saucepan over low heat without stopping stirring until the flour and butter are browned and we just need to add the boiling milk along with the nutmeg and salt, stir and so we would have it ready, just
the mushroom that we have filled with a tablespoon is missing.

To finish we would only have to grate a little cheese of the one we like the most. In this case we are going to put Idiazábal cheese that I like a lot for its smoky flavor.

Gratin in the oven that we have subsequently preheated to 180 degrees for 5 min and once removed from the oven, we season with the seasoned arugula that will bring freshness.

We already have our super tasty starter that we can use in summer!