I don't think "taking a course" is necessary in order to learn assembler. There are tutorials all around the site (and the ASM workshop summaries
, they are the best tutorials you could find in the entire site).
Thus, we are in the 21st century. ASM is a rather archaic language, and teaching it in-depth to people is probably inviable at this point, so i'm not sure that quality "asm courses" still exist.