How to prevent text inside of xml element from being encoded?

I'm having a little trouble with encoding in my C# application.

So, what I'm trying to do is take an xml element and stuff some data inside of it so I can transport that data through a file to another application. However, whenever I go to serialize that element, the xml text inside of the element is encoded. Is there any way to prevent it from being encoded?

So an example of what something I could have is like this:

<element attribute="foo">
    <![CDATA[ some data here.... ]]>
</element>

But what it actually outputs is this:

<element attribute="foo">
    &lt![CDATA[ some data here.... ]] &gt
</element>

Here is my serializer:

XmlDocument doc = new XmlDocument();

StringBuilder xml = new StringBuilder();
XmlSerializer serializer = new XmlSerializer( objToSerialize.GetType() );
XmlWriterSettings settings = new XmlWriterSettings()
{
    OmitXmlDeclaration = true,
    Indent = true
};

using ( StringWriter writer = new StringWriter( xml ) )
using ( XmlWriter xmlWriter = XmlWriter.Create( writer, settings ) )
{
    XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
    ns.Add( "", "" ); // Removes the xsd & xsi namespace declarations from the xml
    serializer.Serialize( xmlWriter, objToSerialize, ns );
}

return xml.ToString()

How can I prevent this from occurring? Thank you!