Initial commit, dashboard settings page seems to work fine.

includes/dashboard/class-settings.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace PluginNamespace;
+
+class Settings {
+
+    /**
+     * Class constructor.
+     *
+     * @since 1.0.0
+     *
+     * @return void
+     */
+    public function __construct() {
+        add_action( 'admin_menu', array( $this, 'append_to_main_dashboard_menu' ), 12 );
+
+        add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
+    }
+
+    /**
+     * Append to the dashboard menu (prevents doubling).
+     *
+     * @since 1.0.0
+     *
+     * @return void
+     */
+    public function append_to_main_dashboard_menu(): void {
+        $parent_slug = 'nmsp-plugin-name-menu-slug';
+        $page_title = __( 'Namespace Plugin Name - Settings', 'nmsp_plugin_name_settings_title' );
+        $menu_title = __( 'Settings', 'nmsp_plugin_name_settings_title' );
+        $capability = 'manage_options';
+        $menu_slug = $parent_slug;
+        $callback = array( $this, 'show_settings_page' );
+
+        add_submenu_page( $parent_slug, $page_title, $menu_title, $capability, $menu_slug, $callback );
+    }
+
+    /**
+     * Show the settings page on the dashboard.
+     *
+     * @since 1.0.0
+     *
+     * @return void
+     */
+    public function show_settings_page(): void {
+        $data = array();
+
+        echo nmsp_plugin_app()->blade->run( 'dashboard.settings', $data );
+    }
+
+    /**
+     * Register and enqueue stylesheets and javascript files.
+     *
+     * @since 1.0.0
+     *
+     * @return void
+     */
+    public function enqueue_scripts(): void {
+        wp_enqueue_style( 'nmsp-plugin-dashboard-css', plugins_url( '../../assets/css/nmsp-plugin-name.css', __FILE__ ), array(), '1.0.0', 'screen' );
+
+        wp_register_script( 'nmsp-plugin-dashboard-js', plugins_url( '../../assets/js/nmsp-plugin-name.js', __FILE__ ), array(), '1.0.0', false );
+        wp_enqueue_script( 'nmsp-plugin-dashboard-js' );
+
+        $payload = array(
+            'wp_ajax_url' => admin_url( 'admin-ajax.php' ),
+            '_nonce'      => wp_create_nonce( NMSP_PLUGIN_NONCE ),
+        );
+        wp_localize_script( 'nmsp-plugin-dashboard-js', 'nmspDashboardApi', $payload );
+    }
+
+}
+
+new Settings();