700g onions, thinly sliced 

2 tablespoons olive oil

50g butter 

2 cloves garlic 

1/2 teaspoon sugar

2 pints beef stock

275ml dry white wine 

2 tablespoons cognac 
For croutons: Bread, Olive oil, Garlic

225 grated gruyere 

Melt oil and butter. 

Add onions, garlic and sugar when very hot. 

Stir for 6 mins until vegetables turn dark. 

Reduce heat to lowest. Leave for 30 mins. 

Pour in stock and wine, stir, scrape pan. 

When simmering, turn down and leave for one hour. 

Add cognac, croutons and cheese to finish.