Preheat oven to 180 °C and grease a gratin dish well. Cut the bread into small cubes and soak in the warm milk.
Remove the skin from the onions, cut them in half diagonally, take out 2/3 of the inner parts, chop half of them finely, fry them in a little light butter with the minced meat, put them with the squeezed out bread, mustard, thyme and egg into a sufficiently large bowl, mix the whole thing well and season it spicily with the spices.
Now fill the onion halves with the mixture, top each with ¼ slice of goat cheese and bacon, place in the gratin dish, pour the clear soup and give cover with aluminum foil.
Cook the dish in the oven for 45 min  remove the foil for the last 10 min to brown.
Serve with : fresh baguette and green leaf salad Drink : a well chilled beer
Tip: Cook only with high quality spices – they are the be-all and end-all in a good dish!