For the filling, fry the salsiz, diced bacon, bread and onions in butter over medium heat for 3 minutes, remove the pan from the heat and add the herbs.
Mix the flour and salt in the bowl and form a well. Whisk the milk, water and eggs together, pour in. Mix and beat until the batter is smooth and bubbles. Mix the meat, herbs and bread mixture into the batter.
Blanch the chard in boiling salted water for 1-2 minutes. Rinse in cold water, drain and lay out on a kitchen towel.
Place 1 tablespoon of each filling in the middle of the leaves. Fold the long sides of the leaves over the filling and roll up.
Place the capuns in another pan. Add the vegetable stock and milk and leave to stand, covered, just below the boiling point for about 15 to 20 minutes.
Arrange the capuns on the plates. In another pan, froth the butter with the cheese over the capuns.