How to ACTUALLY unlock artbook, recipe and get OST!

So, you have completed the game with all achievements, and still cannot find where to get artbook?
Or you're just want to buy these sweet tunes and dissapointed to see you can't do it on Steam?
Worry not, my friend! This guide will get you covered.

So, what do you have to do?

1. Load level 10.
2. Do the secret ending again.
3. Don't skip the credits screen! Look closely: down there is a link and a code to redeem your copy of the artbook.
Here's the link so you don't have to type manually: https://vanripper.itch.io/artbook
Please note: you need a code from credits screen, it's right below the link. This code must be entered in all caps. The wierd letter is K.
4. Download it!
5. Enjoy!

But I bought the artbook on Steam!

Oh, then it's even easier! All you have to do is open the game folder, and it will be there.
If you don't know your game folder location, you can just:
1. Open game library
2. Press RMB on "Helltaker"
3. "Properties"
4. On "Local files" tab there is a "Browse local files" button. It opens the game folder.
5. The artbook is right there!
6. Enjoy!

Okay, but can I get the soundtrack?

Actually, you can!
Music is made by the great man Mittsies. His Youtube is mentioned in credits: https://www.youtube.com/Mittsies

What is much less known, he has a website, where you can actually download or buy his tracks! So, if you want to get downloadable OST, you don't have to use YT-rippers. Just go here:
https://www.mittsies.com/music.html
"Vitality", "Epitomize" and "Luminiscent" are all there in misc tracks. "Apropos" is the 15th track of "Tandem" Album, it's on the bottom of the page, don't miss it!
Site will ask you if you're 18 or older, but only because it contains a page with adult animations. Yeah, Mittsies draws some.

You can also check his itunes: https://music.apple.com/us/artist/mittsies/891169363
And some tracks are on bandcamp: https://mittsies.bandcamp.com

Conclusion

So all that is pretty simple, yet not very obvious. Hope it helped! Have a nice day!
And try that pancakes recipe. It's pretty good. It's actually more blini than pancakes, but it's even better.

I am not a native English speaker, so if you see some blatant errors, please leave them at the comments.

Delivered to you by EasternTime.
Thanks to Potato Sandwich for helping me to figure it out in the first place.
Thanks to Irradiated Irridium, Alcyonaria and naranciaisdead for valuable additions for this guide.

[감자 피자 롤]

Is there a way to view the artbook without going through each file if you use the first method off itch.io?

[EasternTime]

@Wubalubadubdub Well, you supported the developer. That's a plus.

[Yung Oneshot]

Rip to everyone (including me) that bought it off steam, when it's literally free of itch.io

[Remastered Carl Johnson]

Thx, I hope Helltaker 2 will be released someday.

[chrisluvo03]

Helpful, very.

[Luke Malas]

Gracias capo, muy buena guia!

[AmityBlood]

I bought the dlc and then saw that you can get it for free and was like, oh well, why not, it's a good game night as well support lol

[Imploded Nipples]

this is cool

[Al3xCutiePie]

now i don't have to pay! tyty

[Superior Lupus]

Gracias <3