French onion soup

25g butter
1tbsp oil
3 large onions,thinly sliced
2tbsp caster sugar
15g plain flour
1.25l stock
few drops gravy browning
1 small baguette
100g mature cheese,grated

Melt the butter and oil in a large saucepan,add onions and stir so they are coated.Cook over a low heat until soft.Stir in sugar and continue to cook over a low heat for 20 min,stirring often,until they're golden brown.Remove from the heat and stir in the flour.Cook,stirring,for 1 min.Remove from the heat and gradually stir in the stock.Bring back to the boil,cover and simmer for 35-40 min.If you want a deeper colour,carefully add a little gravy browning now-you only need a few drops.To make the croutes.Preheat the grill.Cut 8 slices from the baguette and toast on one side.Turn over sprinkle with grated cheese and grill until melted.Serve on top of the soup.