For the soup, heat the olive oil in a small saucepan over a medium heat and cook the onion for 5 minutes, or until softened but not coloured. Add the garlic and cook for one minute.
Add the spinach and vegetable stock to the pan and season well with salt and freshly ground black pepper. Simmer for 3-4 minutes, then blend with a hand blender until smooth.
For the croûtons, preheat the grill to medium. Drizzle the oil over the baguette slices and top with the goats' cheese.
Place the baguette slices under the grill for five minutes, or until bubbling and golden-brown.
To serve, pour the soup into a bowl, swirl in the double cream and top with the goats' cheese croûtons.