The main ingredients are egg yolks, sugar, and cream. It is often made spicy with paprika, roasted red peppers and egg yolks. Cooled hard-boiled eggs are peeled and halved lengthwise, with the yolks then removed. It is often made with egg yolks and buttermilk instead of potatoes. It forms around fertilized or unfertilized egg yolks. Then add ten or twelve egg yolks. Dressed herring salad is often decorated with grated boiled eggs (whites, yolks, or both). Norwegians, however, also make Hardanger lefse with egg yolks and buttermilk. Some formulas use whole eggs instead of just yolks. Allergic reactions against egg white are more common than reactions against egg yolks. The bottom layer is made of dulce de leche enriched with egg yolks. Lutein is also found in egg yolks and animal fats. Egg yolks specifically contribute to the richness of desserts. Angel food cake is a 19th-century American cake that contains no egg yolks or butter. Yogurt and a mixture of milk and yolks are possible substitutes.