In a saucepan or pot over medium-high heat, add water, butter, salt and bring to a boil.

When it has started boiling, add the flour by slowly sifting it through a sieve and mix with a wooden spoon until a creamy dough is formed.

Turn the heat to low and continue to cook, stirring quickly and intensely, taking care not to let the dough stick to the pan. Continue until the dough stops sticking to the walls of the pan and becomes dense.

Transfer the hot dough to a mixer bowl or food processor with the dough paddle on.

Start the mixer at a low speed and gradually add the mustard, Parmesan, eggs, one by one, until completely incorporated.

Then add the parsley and onion.

Transfer the mixture to a pastry bag once it cooled down a bit. Let the dough stand at room temperature for a quarter of an hour.

Meanwhile, add water to a large pot and bring it to a boil.

When the water started boiling, squeeze the pieces of gnocchi, 3-4 cm each, from the pastry piping bag, and cut each one with the help of a knife.

Make a dozen gnocchi, then boil them for around 3 minutes and remove them with the help of a sieve. Follow by putting them in a bowl greased with a little bit of olive oil and continue the procedure with the rest of the French gnocchi dough. It's best to do them in batches and not over-crowd them in the pot, so they don't stick together while cooking.

Let them cool or put them in the freezer until you are ready to cook.

Prepare the sauce.

In a frying pan on medium heat, add olive oil, garlic and saute for a minute. Add the kale leaves, leeks and continue cooking.

Add ½ cup of water and cook, stirring, until the leaves become soft and the water evaporates, around 7-8 minutes.

Add the butter and mix until it melts. Turn off the heat, add the parmesan, salt, pepper and mix until you get a creamy composition.

Add gnocchi over the sauce, mix and serve.