Whisk the flour, eggs and milk with a whisk and season. Let the dough rise in the refrigerator for half an hour.
In the meantime, heat up a pan with oil and fry the diced ham in it. Transfer the fried ham cubes into a small container.
Peel the onion, cut in half, cut into half rings and fry in the same pan until golden brown.
Take the dough out of the fridge and stir in the diced ham, onion rings and Gouda cheese. Heat the pan again and pour in a ladle of batter. Bake the first side until golden brown, turn and also bake the second side until golden brown. Repeat this until the batter is used up.