Clean and wash spring onions and cut into fine rings. Heat the fat in a pot and sauté the spring onions. Dust with flour, sweat briefly and pour on the stock while stirring. Bring the soup to the boil and simmer for about 5 minutes. In the meantime, cut the baguette into slices and roast in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 5-10 minutes. Roast pine nuts in a pan without fat and let them cool down. Wash herbs, dab dry and chop except for something to garnish.
Stir the herbs and 200 g cream into the soup and puree. Season herb soup with salt and pepper. Spread baguette slices with pesto and sprinkle with pine nuts. Beat 50 g cream until semi-stiff. Arrange the soup in 4 deep bowls and stir in a dollop of cream each. Sprinkle with remaining herbs and garnish. Serve with pesto crostini