Your layout is incorrect, it should show how the reference time is represented in the format you want, where the reference time is Mon Jan 2 15:04:05 -0700 MST 2006.
Your layout should be:
"02-Jan-2006 15:04:05"
Note the 05 for the seconds part. And since you specified the hours as 15, that is 24-hour format. 3 or 03 is for the 12-hour format.
fmt.Println(time.Now().Format("02-Jan-2006 15:04:05"))
For me it prints:
03-Mar-2016 13:03:10
Also note Jan for months, JAN is not recognized. If you want uppercased month, you may use strings.ToUpper():
fmt.Println(strings.ToUpper(time.Now().Format("02-Mar-2006 15:04:05")))
Output:
03-MAR-2016 13:03:10
Also note that on the Go Playground the time is always set to a constant when your application is started (which is 2009-11-10 23:00:00 +0000 UTC).