Place a long strip of foil or parchment paper on the counter to drop your cookies on.

In a medium sized pot, add the butter, evaporated milk and sugar to the pot. Put the pot on the stovetop over medium heat. Stir mixture occasionally as you measure out the peanut butter and get the oats ready. Once the mixture on the stove starts to bubble on top and boil, start the timer and boil for exactly 1-minute. Do not boil any longer. During that minute, stir the mixture constantly as it comes to a full, rolling boil. Once the minute is up, remove the pot from the stove.

Immediately stir in the peanut butter, salt and marshmallow compound (or vanilla extract) to the mixture, and stir until combined. Stir in oats, one cup at a time, making sure each cup is completely mixed into the cookie mixture, before adding the next cup of oats. Only use enough oats that the cookie consistency is still wet, but thick enough that they will set. I used 2-3/4 cups of oats. Fold in the mini marshmallows.

Use a standard sized cookie scoop to drop cookies onto the foil. While cookies are still warm, you can use the back of a spoon to smooth and shape your cookies into perfect cookie shapes. Allow cookies to cool and set before transferring to an airtight container.