Untitled

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
   <title>Xy_Theme</title>
   <parent>Magento/backend</parent>
</theme>

<?php
  MagentoFrameworkComponentComponentRegistrar::register(
  MagentoFrameworkComponentComponentRegistrar::THEME,
  'adminhtml/XXX/yyy',
  __DIR__
);

<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="admin-1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<head>
  <title>Admin Title</title>
</head>
<body>
  <referenceContainer name="header">
    <block class="MagentoBackendBlockPageHeader" name="logo" before="-">
      <arguments>
        <argument name="show_part" xsi:type="string">logo</argument>
        <argument name="edition" translate="true" xsi:type="string">Community Edition</argument>
        <argument name="logo_image_src" xsi:type="string">images/my-logo.svg</argument>
        <argument name="logo_alt" xsi:type="string">My Admin</argument>
      </arguments>
    </block>
  </referenceContainer>
</body>