diff --git a/aws_lambda_powertools/utilities/data_classes/cognito_user_pool_event.py b/aws_lambda_powertools/utilities/data_classes/cognito_user_pool_event.py
index 79c43a8b701..c85515a31d5 100644
--- a/aws_lambda_powertools/utilities/data_classes/cognito_user_pool_event.py
+++ b/aws_lambda_powertools/utilities/data_classes/cognito_user_pool_event.py
@@ -575,13 +575,10 @@ def scopes_to_suppress(self, value: list[str]):
 
 class ClaimsAndScopeOverrideDetails(GroupConfigurationBase):
     @property
-    def id_token_generation(self) -> TokenClaimsAndScopeOverrideDetails | None:
-        id_token_generation_details = self._data.get("idTokenGeneration")
-        return (
-            None
-            if id_token_generation_details is None
-            else TokenClaimsAndScopeOverrideDetails(id_token_generation_details)
-        )
+    def id_token_generation(self) -> TokenClaimsAndScopeOverrideDetails:
+        if self._data.get("idTokenGeneration") is None:
+            self._data["idTokenGeneration"] = {}
+        return TokenClaimsAndScopeOverrideDetails(self._data["idTokenGeneration"])
 
     @id_token_generation.setter
     def id_token_generation(self, value: dict[str, Any]):
@@ -597,13 +594,10 @@ def id_token_generation(self, value: dict[str, Any]):
         self._data["idTokenGeneration"] = value
 
     @property
-    def access_token_generation(self) -> TokenClaimsAndScopeOverrideDetails | None:
-        access_token_generation_details = self._data.get("accessTokenGeneration")
-        return (
-            None
-            if access_token_generation_details is None
-            else TokenClaimsAndScopeOverrideDetails(access_token_generation_details)
-        )
+    def access_token_generation(self) -> TokenClaimsAndScopeOverrideDetails:
+        if self._data.get("accessTokenGeneration") is None:
+            self._data["accessTokenGeneration"] = {}
+        return TokenClaimsAndScopeOverrideDetails(self._data["accessTokenGeneration"])
 
     @access_token_generation.setter
     def access_token_generation(self, value: dict[str, Any]):
@@ -622,13 +616,17 @@ def access_token_generation(self, value: dict[str, Any]):
 class PreTokenGenerationTriggerEventResponse(DictWrapper):
     @property
     def claims_override_details(self) -> ClaimsOverrideDetails:
-        return ClaimsOverrideDetails(self.get("claimsOverrideDetails") or {})
+        if self._data.get("claimsOverrideDetails") is None:
+            self._data["claimsOverrideDetails"] = {}
+        return ClaimsOverrideDetails(self._data["claimsOverrideDetails"])
 
 
 class PreTokenGenerationTriggerV2EventResponse(DictWrapper):
     @property
     def claims_scope_override_details(self) -> ClaimsAndScopeOverrideDetails:
-        return ClaimsAndScopeOverrideDetails(self.get("claimsAndScopeOverrideDetails") or {})
+        if self._data.get("claimsAndScopeOverrideDetails") is None:
+            self._data["claimsAndScopeOverrideDetails"] = {}
+        return ClaimsAndScopeOverrideDetails(self._data["claimsAndScopeOverrideDetails"])
 
 
 class PreTokenGenerationTriggerEvent(BaseTriggerEvent):
diff --git a/tests/unit/data_classes/required_dependencies/test_cognito_user_pool_event.py b/tests/unit/data_classes/required_dependencies/test_cognito_user_pool_event.py
index 41ee52d915e..af84b3f8982 100644
--- a/tests/unit/data_classes/required_dependencies/test_cognito_user_pool_event.py
+++ b/tests/unit/data_classes/required_dependencies/test_cognito_user_pool_event.py
@@ -187,7 +187,7 @@ def test_cognito_pre_token_generation_trigger_event():
 
     expected_claims = {"test": "value"}
     claims_override_details.claims_to_add_or_override = expected_claims
-    assert claims_override_details.claims_to_add_or_override["test"] == "value"
+    assert parsed_event.response.claims_override_details.claims_to_add_or_override["test"] == "value"
 
     claims_override_details.claims_to_suppress = ["email"]
     assert claims_override_details.claims_to_suppress[0] == "email"
@@ -229,6 +229,10 @@ def test_cognito_pre_token_v2_generation_trigger_event():
     assert parsed_event.request.scopes == raw_event["request"]["scopes"]
 
     claims_scope_override_details = parsed_event.response.claims_scope_override_details
+    # Test that accessing id_token_generation and access_token_generation properties initialize empty dicts
+    assert claims_scope_override_details.id_token_generation.claims_to_add_or_override == {}
+    assert claims_scope_override_details.access_token_generation.claims_to_add_or_override == {}
+
     claims_scope_override_details.id_token_generation = claims_scope_override_details.access_token_generation = {}
     assert claims_scope_override_details.id_token_generation.claims_to_add_or_override == {}
     assert claims_scope_override_details.id_token_generation.claims_to_suppress == []
@@ -246,8 +250,14 @@ def test_cognito_pre_token_v2_generation_trigger_event():
     expected_claims = {"test": "value"}
     claims_scope_override_details.id_token_generation.claims_to_add_or_override = expected_claims
     claims_scope_override_details.access_token_generation.claims_to_add_or_override = expected_claims
-    assert claims_scope_override_details.id_token_generation.claims_to_add_or_override["test"] == "value"
-    assert claims_scope_override_details.access_token_generation.claims_to_add_or_override["test"] == "value"
+    assert (
+        parsed_event.response.claims_scope_override_details.id_token_generation.claims_to_add_or_override["test"]
+        == "value"
+    )
+    assert (
+        parsed_event.response.claims_scope_override_details.access_token_generation.claims_to_add_or_override["test"]
+        == "value"
+    )
 
     claims_scope_override_details.id_token_generation.claims_to_suppress = (
         claims_scope_override_details.access_token_generation.claims_to_suppress