Wash chicken and pat dry. Season with salt and pepper and paprika. Using a large frying pan brown chicken in 1 tsp butter. Transfer to crockpot. Pour broth and sherry into pan. Stir to loosen brown bits. Pour over chicken. Season with tarragon. Cover. Cook on low for 8 hours. Just before serving, saute mushrooms in remaining butter until glazed. Combine cornstarch with equal amount of cold water. Turn crockpot to high. When sauce is simmering, stir in cornstarch mixture. Cook until thickened. Add sauteed mushrooms and artichoke hearts and heat and serve.