<div id="ingredients" class="ingredients">
      <h2 class="tk-freight-sans-pro">Ingredients</h2>
      <input type="text" placeholder="Ingredient">
      <input type="text" placeholder="Ingredient">
      <input type="text" placeholder="Ingredient">
      <br>
      <button class="button" onclick="addIngredient();">Add Ingredient</button>
    </div>

function addIngredient() {
        var list = document.getElementById("ingredients")
        list.innerHTML += "<input type="text" placeholder="Ingredient">"
     }