As `fncychap` has no such chapter style, and using the `memoir` class will cause a lot conflicts with my current settings (`book` class), how to make this style (perhaps using the `titlesec` package)?

Table of contents and Chapter style:

![enter image description here](https://i.stack.imgur.com/7qoys.png)
and
![I](https://i.stack.imgur.com/yeTjN.png)

Here are my setting for chapters:

```
\usepackage[ ]{titlesec}  
\titleformat{\chapter}[display]
{\normalfont\LARGE\bfseries }{\chaptertitlename\  \thechapter}{10pt}{\huge}
\titlespacing*{\chapter}{0pt}{40pt}{40pt}  % left, vertical, skip

```