How to serialize datetime value in C# ASP.NET?

I am using ASP.NET MVC5 framework to build an app. I need a function to allow me to easily convert ad object to a json string.

I found this awsome class that will do exactly what I need.

using System.Web.Script.Serialization;
namespace App.Support
{
    public static class JsonHelpers
    {
        public static string ToJson(this object obj)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            return serializer.Serialize(obj);
        }

        public static string ToJson(this object obj, int recursionDepth)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            serializer.RecursionLimit = recursionDepth;
            return serializer.Serialize(obj);
        }
    }
}

The only issue that I am not sure how to workaround is datetime values.

after reading a list from a database with some datetime column I want to convert the list to json. When I use JsonHelper.ToJson(mylist); the datetime fields will look like this Date(1456182878660)

How can I convert that value to YYYY-MM-DD- H:i:s format? when I parse the json string using jQuery the datetime value looks like this /Date(1456182878660)/