Slice the onions, then add the butter + oil in a deep-bottomed pan.
Add the onions, season with salt, mix well + sautée on a medium heat until softened (15-20 minutes - stirring regularly to avoid burning).
Add the sugar, then cook for a further 10-20 minutes until golden + soft.
Mince the garlic + sautée until fragrant.
Add the plain flour, stir well until incorporated
Increase the heat, then add the wine gradually to deglaze the pan, stirring well as you go.
Add the hot vegetable stock, rosemary, thyme + bay, then simmer for 30 minutes.
Slice the baguette + toast under the grill with a splash of oil / in toaster.
Ladle the soup into heatproof bowls, put the bread on top, then cover with grated cheese.
Place under the grill until melted, then top with finely chopped chives + enjoy!
