Ruby route for custom controller

Ruby route for custom controller

So I want when I access: site.com/panel to look into
/app/controller/panel/index_controller.rb
Before I start I'm new to ruby, I started a couple hours ago
So in my routes.rb I have this
namespace :panel do
root 'index#index'
resources :index
end
And I created a file called index_controller.rb in
/app/controller/panel/index_controller.rb which looks like this
class IndexController < ApplicationController
def index
@foo = "Foo"
end
end
Now when I go to site.com/panel I get this: superclass mismatch for class
IndexController
What I did wrong? Also can I setup diffrent views and layout here to use
for the controllers inside /app/controller/panel/*_controller.rb