engine/app/models/extensions/page/render.rb

module Models
  module Extensions
    module Page
      module Render

        def render(context)
          self.template.render(context)

          if self.layout
            self.layout.template.render(context)
          else
            ::Liquid::Template.parse("{{ content_for_layout }}").render(context)
          end
        end

      end
    end
  end
end