How to make notepad++ the default editor for a Windows batch file?

Change the program associated to the "Edit" verb for batch files:

• Run RegEdit (as admin)
• Navigate to HKEY_CLASSES_ROOT\batfile\shell\edit\command.
• Modify the Default and change Value Data from %SystemRoot%\System32\NOTEPAD.EXE %1 to "C:\Program Files (x86)\Notepad++\notepad++.exe" "%1"
• Close RegEdit.
• Right-click -> "Edit" should now open batch files in NotePad++.

Note: You may have to adjust your path to Notepad++.exe if it resides in a different folder on your system.

Also note: This is a system-wide change.