Build one Unreal Engine Plugin only
Example building Unreal Midi on my machine:
G:\5.0.3-release\Engine\Build\BatchFiles>RunUAT.bat BuildPlugin -plugin="G:\5.0.3-release\Engine\Plugins\Marketplace\MidiAsset\MidiAsset.uplugin" -package="F:\temp\UnrealMidi" -TargetPlatforms=Win64