First - gather your ingredients!
Cream the butter and the sugars together. Add in the eggs. Mix well.
Then, add in the baking soda, vanilla, and agave. Mix well.
Add in the peanut butter and then slowly add in the oats one cup at a time. Mix well. Stir in the chocolate chips.
Then, lay out the mixture in a very large baking sheet, or in a 9x13 glass pan - be sure the sheet cookie has room to expand (this was my error). Top with the M&Ms. Bake at 350 degrees for 25-30 minutes.
Okay - my mess. What happened is I used a small pan - and the sheet cookie was expanding over the edge, making a huge mess in my oven. Augh. What to do. I grabbed my 9x13 baking dish, took out the pan and pushed everything into a big bowl. I stirred it up (even though it was already 1/2 baked) and then pressed it into the 9x13 pan and continued baking it. Turned out to be really good, just didn't look like a traditional monster cookie.
Done! Even after that little (or big) mess, the monster cookies were still great!