import re
s = "Example=N      ; Comment Line One error=\n\n; Comment Line Two.\n\nDesired=\n"
config_value = 'Example'
pattern=r'(?sm)^{}=(.*?)(?=[\r\n]+\w+=|\Z)'.format(config_value)
match = re.search(pattern, s)
if match:
    print(match.group(1))