Make Middleman compile coffee-script using bare mode.

config.rb

#
# Add the following to Middleman's config.rb:
# 

CoffeeScript.class_eval do
  class << self
    def compile_with_bare(*args)
      options = args.pop if args.last.is_a?(Hash)
      (options ||= {})[:bare] = true
      args << options
      compile_without_bare(*args)
    end

    alias_method :compile_without_bare, :compile
    alias_method :compile, :compile_with_bare
  end
end

Thank for providing a solution. Why is Tilt::CoffeeScriptTemplate.default_bare = true not working?

Even easier (actually it is working):

Tilt::CoffeeScriptTemplate.default_bare = true