has_many to has_many, add attribute to the join table

Hi I have a primary model, recipes with a has_many association with ingredients, which also has_many recipes, my join table is recipes_ingredients, the join table has the columns recipe_id, ingredient_id, and quantity. The quantity is just a string for how many times that ingredient will be used in that recipe.

I have a form that creates the recipe and saves it in the database at the same time it creates and saves any ingredients that are given in the form with a nested attribute... I cannot for the life of me figure out how to add the quantity for this join-table using this same form. I would appreciate any help you can afford me... thank you so much in advance.

**models
class Recipe < ApplicationRecord
belongs_to :user
has_many :recipe_ingredients
has_many :ingredients, through: :recipe_ingredients
validates :name, :content, :cook_time, presence: true

  def ingredients_attributes=(ingredients_hash)
    ingredients_hash.each do |i, ingredients_attributes|
        if ingredients_attributes[:name].present?
            ingredient = Ingredient.find_or_create_by(name: 
         ingredients_attributes[:name].capitalize!)
            if !self.ingredients.include?(ingredient)
                self.recipe_ingredients.build(:ingredient => 
        ingredient)
            end
        end
    end
end


class Ingredient < ApplicationRecord
has_many :recipe_ingredients
has_many :recipe, through: :recipe_ingredients
validates :name, presence: true

class RecipeIngredient < ApplicationRecord
belongs_to :ingredient 
belongs_to :recipe
end

 ***form
  <%= form_with(model: instruction, local: true) do |form| %>
   <% if instruction.errors.any? %>
   <div id="error_explanation">
  <h4><%= pluralize(instruction.errors.count, "error") %> prohibited 
   this instruction from being saved:</h4>

  <ul>
  <% instruction.errors.full_messages.each do |message| %>
    <li><%= message %></li>
  <% end %>
  </ul>
   </div>
    <% end %>

     <div class="container">
     <div class="row">
     <div class="col-sm-6">
      <h3 class="text-center">Recipe</h3>
      <div class="fields">
        <%= form.label :name %><br>
        <%= form.text_field :name, :placeholder => "Name" %><br>
        <%= form.label "Instructions"  %><br>
        <%= form.text_area :content, :placeholder => "Recipe 
        Instructions" %><br>
        <%= form.label :cook_time %><br>
        <%= form.text_field :cook_time, :placeholder => "(ex,. 45 
        mins)" %><br>
        <%= form.hidden_field :user_id, value: params[:user_id] %>
      </div>
      </div>

       <div class="col-sm-6">
        <h3 class="text-center">Ingredients</h3>
        <div class="row">
          <div class="col-sm-6 checkbox">
                <%= form.collection_check_boxes(:ingredient_ids, 
            Ingredient.all, :id, :name) %> 
            </div>
            <div class="col-sm-6">
                <%= form.fields_for :ingredients do 
            |ingredient_builder| %>
                    <%= ingredient_builder.text_field :name %><br>
                <% end %>
              </div>
            </div>
        </div>
       </div>

        <div class="row justify-content-center submit-row">
         <div class="fields text-center">
          <%= form.submit %>
       </div>
      </div>


     </div>