diff --git a/src/quart/app.py b/src/quart/app.py
index 879440c..c9d68fb 100644
--- a/src/quart/app.py
+++ b/src/quart/app.py
@@ -21,7 +21,6 @@
     Optional,
     overload,
     TypeVar,
-    Union,
 )
 from urllib.parse import quote
 from weakref import WeakSet
@@ -41,6 +40,7 @@
 
 from .asgi import ASGIHTTPConnection, ASGILifespan, ASGIWebsocketConnection
 from .cli import AppGroup
+from .config import Config
 from .ctx import (
     _AppCtxGlobals,
     AppContext,
@@ -207,6 +207,7 @@ class Quart(App):
     test_client_class: type[TestClientProtocol]  # type: ignore[assignment]
 
     aborter_class = Aborter
+    config_class = Config
     app_ctx_globals_class = _AppCtxGlobals
     asgi_http_class = ASGIHTTPConnection
     asgi_lifespan_class = ASGILifespan
@@ -1100,7 +1101,7 @@ def ensure_async(self, func: Callable[P, T]) -> Callable[P, Awaitable[T]]:
         ...
 
     def ensure_async(
-        self, func: Union[Callable[P, Awaitable[T]], Callable[P, T]]
+        self, func: Callable[P, Awaitable[T]] | Callable[P, T]
     ) -> Callable[P, Awaitable[T]]:
         """Ensure that the returned func is async and calls the func.
 
diff --git a/tests/test_app.py b/tests/test_app.py
index 02f012d..19fb4c3 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -11,6 +11,7 @@
 from werkzeug.wrappers import Response as WerkzeugResponse
 
 from quart.app import Quart
+from quart.config import Config
 from quart.globals import session, websocket
 from quart.sessions import SecureCookieSession, SessionInterface
 from quart.testing import no_op_push, WebsocketResponseError
@@ -408,3 +409,8 @@ async def index() -> str:
         assert serving == [1]
     assert shutdown
     assert serving == [1, 2]
+
+
+def test_app_config_class() -> None:
+    app = Quart(__name__)
+    assert isinstance(app.config, Config)