Trim leaves, stems, and fuzzy chokes from artichokes.
Drop artichoke hearts into a bowl of ice water mixed with lemon juice and olive oil.
Bring a large pot of water to a boil and add salt. Drain hearts and add to boiling water; cook until tender. Drain.
In a pan over medium-high heat, melt butter. Add onion and stir until golden. Stir in flour; cook, stirring often, 3 to 5 minutes. Add chicken broth and the artichoke hearts; stir until mixture boils and thickens, 15 to 20 minutes.
Whirl mixture in a blender until smooth. Return to pan and heat through. Add whipping cream and salt and pepper to taste. Ladle into bowls and garnish with chopped chervil.