Plasma Splashscreen, customized for the Plasma Theme "Charlie", which you can download: Here
The text "Hello Charlie", you can easily change, in the following way:
Home Folder (Hidden Files) /. Local / share / plasma / look-and-feel / org.kde.Charlie.desktop / contens / splash / Splash.qml
Line 211, change the text Hello Charlie! in the text you want.
The author of the wallpaper: charlie-henson: Here