Angular update model from directive

HTML

<script src="http://code.angularjs.org/1.1.0/angular.min.js"></script>
<div ng-app="App">
    <div ng-controller="Ctrl" ng-init="init()">
        <p>Foo in Ctrl: {{foo}}</p>  
        <toggle label="Foo" ng-model="foo"></toggle>
    </div>    
</div>

JavaScript

var app = angular.module('App', []);

function Ctrl($scope) {
    $scope.init = function() {
        $scope.foo = true
    }
}

app.directive('toggle', function() {
    return {
        restrict: 'E',
        replace: true,
        transclude: true,
        scope: {
            label: '@',
            ngModel: '='
        },
        template: 
            '<div style="cursor: hand; cursor: pointer">{{label}}: {{ngModel}}</div>',
        link: function(scope, element, attrs, controller) {
            element.bind('click', function() {
                scope.ngModel = false;
                attrs.$set('ngModel', false);
                console.log('plz', attrs.ngModel);
            });
        }
    };
});