1
: In a large saucepan, heat oil over medium heat. Add leeks, onions, garlic and thyme. Cover and cook 20 minutes, stirring occasionally, until very soft.
2
: Add stock. Bring to a boil. Reduce heat and simmer for 10 minutes. Remove from heat. Purée with an immersion blender or food processor until smooth.
3
: Stir in evaporated milk and reheat soup until hot but not boiling. Season with salt, pepper and cayenne. Serve, garnished with ham and cheese.