Create a simple DOM and having it serialize to:

 <?xml version="1.0" ?>
 <root>
     <element>
         Some text here
     </element>
 </root>

DOM = XMLObject["Document"][{XMLObject["Declaration"]["Version" -> "1.0","Encoding" -> "utf-8"]},
XMLElement["root", {}, {XMLElement["element", {}, {"Some text here"}]}], {}];
ExportString[DOM, "XML", "AttributeQuoting" -> "\""]