Should be simple, but whatever I try returns null:
const string key = \"system.web\";
var sectionTry1 = WebConfigurationManager.GetSection(key);
var sectionTry
Was being an idiot - system.web is not a config section but a config group. If I change the key to an actual section, then both methods work fine. Here's the one using ConfigurationManager:
const string outputCacheSettingsKey = "system.web/caching/outputCacheSettings";
var outputCacheSettingsSection = ConfigurationManager.GetSection(outputCacheSettingsKey) as OutputCacheSettingsSection;