Dart – Convert JSON string to a Dart List<Type>

I am successfully receiving a JSON object in the following function:

class PostsAPI extends WebService {
  final userStorage = UserStorage();

  Future<dynamic> getFeedPosts() async {
    final token = await userStorage.getUserToken();

    final response = await get(
      endpoint: '/api/posts',
      token: token,
    );

    if (response.statusCode != 200) {
      if (response.statusCode == 500) {
        throw PostsServerFailure();
      }
      throw PostsRequestFailure();
    }

    return response.body;
  }
}

My issue is, I simply cannot seem to convert the JSON into a List of type Post:

Future<List<Post>> getFeedPosts() async {
  final postsAPI = await _postsAPI.getFeedPosts();

  final posts = List<Post>.from(postsAPI['posts'].map(Post.fromJson())); // **HERE**

  return posts;
}

No matter what I attempt, I always end up with an error in the conversion.

Also, here is my Post fromMap and fromJson:

factory Post.fromMap(Map<String, dynamic> map) {
  return Post(
    author: Author.fromMap(map['author'] as Map<String, dynamic>),
    contentURL: (map['url'] ?? '') as String,
    uploadTime: DateTime.parse((map['created_at'] ?? '') as String),
    //videoTimeLength: map['length'] ?? '',
    gameName: (map['game'] ?? '') as String,
    description: (map['description'] ?? '') as String,
    viewCount: map['views'] as int,
    likeCount: map['likes'] as int,
    //comments: Comment.fromMap(map['comments']),
  );
}

factory Post.fromJson(dynamic source) =>
    Post.fromMap(json.decode(source as String) as Map<String, dynamic>);

Also, here is an example of the JSON i’m trying to receive:

{
  "success": true,
  "posts": [
     {
        "id": 38,
        "likes": 60,
        "views": 0,
        "createdAt": "2023-02-15T21:19:47.963Z",
        "content": {
            "id": 28,
            "url": "https://res.cloudinary.com/example.jpg"
        },
        "comments": {
            "count": 0
        },
        "game": {
            "id": 3,
            "name": "Minecraft"
        },
        "user": {
            "id": 5,
            "username": "teste1",
            "avatar_border": {
                "id": 1,
                "name": "delicate_savage",
                "createdAt": "2023-03-06T22:46:19.998Z",
                "updatedAt": "2023-03-06T22:46:21.842Z",
                "publishedAt": "2023-03-06T22:46:21.840Z"
            },
            "background": {
                "id": 1,
                "name": "background_5",
                "createdAt": "2023-03-06T22:45:57.978Z",
                "updatedAt": "2023-03-06T22:46:02.602Z",
                "publishedAt": "2023-03-06T22:46:02.599Z"
            },
            "profile_pic": null
        }
      },
      {
        "id": 37,
        "likes": 5003,
        "views": 0,
        "createdAt": "2023-02-15T21:18:38.451Z",
        "content": {
            "id": 29,
            "url": "https://res.cloudinary.com/example.jpg"
        },
        "comments": {
            "count": 0
        },
        "game": {
            "id": 4,
            "name": "Black ops 2"
        },
        "user": {
            "id": 8,
            "username": "mini",
            "avatar_border": {
                "id": 3,
                "name": "quit_while_youre_ahead",
                "createdAt": "2023-03-06T22:46:34.792Z",
                "updatedAt": "2023-03-06T22:46:35.630Z",
                "publishedAt": "2023-03-06T22:46:35.628Z"
            },
            "background": {
                "id": 1,
                "name": "background_5",
                "createdAt": "2023-03-06T22:45:57.978Z",
                "updatedAt": "2023-03-06T22:46:02.602Z",
                "publishedAt": "2023-03-06T22:46:02.599Z"
            },
            "profile_pic": null
        }
      },
    }
  ]
}

Any help would be very much appreciated!