Final answer:
Sugar is the main ingredient in most icings, essential for creating a sweet and smooth consistency. It is also a primary ingredient in homemade ice cream and many other foods, as recognized by the FDA.
Step-by-step explanation:
The ingredient that serves as the basis for most icings is sugar. In concocting a delicious frosting for cakes or other desserts, sugar is often combined with various dairy products like butter or cream to achieve a smooth, spreadable consistency. When it comes to the process of making other sweet treats, such as homemade ice cream, the combination of heavy cream, whole milk, sugar, and chosen flavors is fundamental. Whether one is baking at home or in a professional setting, sugar is a key component on the FDA's list of ingredients used in food preparation.