- Boil the chicken and keep the stock. Cut chicken into small pieces. In a large bowl add the copped chicken pieces, chopped peppers, salt and pepper, mayonnaise and mushrooms. Stir together. Melt butter and add the onion and almonds and cook until the onion turns golden brown. Add flour, then gradually add stock until it becomes a thick sauce. Pour over ingredients and stir thoroughly. Lastly, add champignons.