Texture taken from Hidden Carina Nebula. Big credit to them for making this amazing texture pack for the overworld.

Just using the Hidden Carina Nebula texture pack isn't enough, you need to find the texture and use it to replace the end sky texture using the instructions near the bottom of the page.

Versions 1.2 and 1.0 work with optifine, though versions 1.1 and 1.3 don't work with optifine.

 

Fabric version here.

Use with a resource pack! It won't work without one that adds a custom end sky.

I made a resource pack here that uses a custom sky texture, so you won't have to edit your own resource pack:

For version 1.1 through 1.3:

Unless you are using the resource pack that I made, you need the file assets/minecraft/textures/environment/custom_end_sky.png in your resource pack to be a custom sky image from a custom sky resource pack, which you can find in the assets/minecraft/optifine/sky/world0 folder. The image should look like 6 images in 1 - one for each side of the skybox.

For version 1.0, the file needs to be named end_sky.png instead of custom_end_sky.png