Stuffed Baked Onions

Preheat the oven to 180 °C. Remove the dirty outer skin from the onions. Carefully cut off the top quarter of each onion and place it back on top. Pour coarse salt into a baking dish, place the onions on top, put them in the preheated oven, and bake for 45 minutes.

In a saucepan over medium heat, melt the butter, add the flour, and stir with a whisk for half a minute. While continuously stirring, pour in all the milk, reduce the heat to minimum, add a pinch of salt and mace, and slowly cook for 10 minutes, stirring constantly with a whisk. Then remove from heat and let cool partially.

Reduce oven temperature to 160 °C. Remove the onions from the baking dish and carefully scoop out the insides of the onions with a spoon. Leave the last layer of flesh and the skin. Finely chop half of the scooped-out onion parts. Use the other half for another dish or discard.