.../modules/system/config/schema/system.schema.yml | 11 +++++++
 .../system/src/Plugin/Block/SystemMenuBlock.php    | 38 +++++++++++-----------
 2 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/core/modules/system/config/schema/system.schema.yml b/core/modules/system/config/schema/system.schema.yml
index 2e9219d..46198c1 100644
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -375,6 +375,17 @@ block.settings.system_branding_block:
       type: boolean
       label: 'Use site slogan'
 
+block.settings.system_menu_block:
+  type: block_settings
+  label: 'Branding block'
+  mapping:
+    level:
+      type: integer
+      label: 'Starting level'
+    depth:
+      type: integer
+      label: 'Maximum number of levels'
+
 condition.plugin.request_path:
   type: condition.plugin
   mapping:
diff --git a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
index 545f896..26677d6 100644
--- a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
@@ -78,25 +78,6 @@ public static function create(ContainerInterface $container, array $configuratio
   /**
    * {@inheritdoc}
    */
-  public function defaultConfiguration() {
-    // Modify the default max age for menu blocks: modifications made to menus,
-    // menu links and menu blocks will automatically invalidate corresponding
-    // cache tags, therefore allowing us to cache menu blocks forever. This is
-    // only not the case if there are user-specific or dynamic alterations (e.g.
-    // hook_node_access()), but in that:
-    // 1) it is possible to set a different max age for individual blocks, since
-    //    this is just the default value.
-    // 2) modules can modify caching by implementing hook_block_view_alter()
-    return array(
-      'cache' => array('max_age' => \Drupal\Core\Cache\Cache::PERMANENT),
-      'level' => 1,
-      'depth' => 0,
-    );
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function blockForm($form, FormStateInterface $form_state) {
     $config = $this->configuration;
 
@@ -173,6 +154,25 @@ public function build() {
   /**
    * {@inheritdoc}
    */
+  public function defaultConfiguration() {
+    // Modify the default max age for menu blocks: modifications made to menus,
+    // menu links and menu blocks will automatically invalidate corresponding
+    // cache tags, therefore allowing us to cache menu blocks forever. This is
+    // only not the case if there are user-specific or dynamic alterations (e.g.
+    // hook_node_access()), but in that:
+    // 1) it is possible to set a different max age for individual blocks, since
+    //    this is just the default value.
+    // 2) modules can modify caching by implementing hook_block_view_alter()
+    return array(
+      'cache' => array('max_age' => \Drupal\Core\Cache\Cache::PERMANENT),
+      'level' => 1,
+      'depth' => 0,
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function getCacheKeys() {
     // Add a key for the active menu trail.
     $menu = $this->getDerivativeId();