For sauce: Melt butter over low heat. Add flour. Cook, stirring, 1-2 minutes. Remove skillet from heat and add warm milk, stirring until smooth. Return to heat, bring to a boil, stirring constantly. Season with salt, ground black pepper, nutmeg, ground cloves and cinnamon. Reduce heat and simmer until thickened.
Cut the apples into quarters, remove the core, cut the flesh into thin slices. Peel the onion and cut into thin half rings.
Finely chop the herbs and onions. Coarsely grate 100 g of cheddar, mix with breadcrumbs and brown sugar.
Grease a small ovenproof dish with olive oil. Mix all the onions, apples and greens, put in a mold and bake at 180 ° C for 30-40 minutes. plus 2 min. under the grill