Onion Tarte Tatin

|Tasty savoury variation on a French classic.|red onion|For the filling:6 medium red onions2 tablespoon olive oil4 sprigs of thyme de-stalked75g strong cheddar gratedFor the crust:250g plain flour1 teaspoon baking powder1 teaspoon salt1 teaspoon mustard powder100ml milk50g butter melted1 egg beaten|Pre-heat the over to 180C. Prepare a 20-23cm pie dish with butter and set aside. Remove the papery outer onion skin from the onions then slice in half and then in half again through the root to quarter them.In a large pan heat the oil add the onions. Cook on a medium heat for about 30 minutes stiring regularly till soft. Add salt and pepper to season and the thyme leaves. Stir through the cheese.Make the dough: put all the dry ingredients (flour baking powder salt and mustard powder) in a large bowl and mix well. In a separate bowl mix together the wet ingredients (egg milk and butter) until well combined. Add the dry ingredients to the wet mixture gradually until they are all incorporated and you have a sticky dough.Add the onion mixtured to your prepared pie dish and make the top as level as you can.With floured hands place the dough on top of the onion mixture and make it as level as you can.Bake the tart for 20-25 minutes until the crust is set and golden. Once cooked remove from the oven and set aside to cool slightly. Place a plate on top of the pie dish and invert it so the tart flips out and the dough crust is now on the bottom.|10.00 minutes|6|