Mix the flour, semolina and salt in a bowl, make a well in the middle. Combine the milk, water and eggs, gradually pour into the well while stirring, mix everything together and beat until the dough starts to bubble. Cover and leave to stand at room temperature for approx. 30 mins.
In batches, spread the dough onto a wet chopping board using a spatula. Scrape off long, thin strips of dough and drop them straight into the boiling salted water.
As soon as the Spätzli rise to the surface, remove with a slotted spoon and keep warm.