Read over the entire recipe. Line two baking sheets with wax or parchment paper. Measure out all of your ingredients. Have your thermometer, timer, and large cookie scoop ready. (This recipe is about timing, and having everything ready to go helps)

In a large bowl, whisk together sugar, unsweetened cocoa powder, and cream of tartar until no lumps remain. Set aside

In a large, deep non-stick skillet melt butter over medium-low heat.

Stir in milk.

Pour sugar mixture into skillet and stir using a rubber spatula.

Stir until all sugar has dissolved, being sure to scrape down the sides of the pot. Increase the heat if needed but do not simmer. (I check for granules by rubbing the mixture between my fingers. If it feels smooth, you're ready to move on to the next step. For the next step, get your thermometer and make sure your timer is ready for 2 minutes.)

Once the sugar has melted, increase the heat to a rolling boil over medium heat while continuing to stir. (A rolling boil means the middle should have large rolling bubbles and not just simmering)

As soon as the mixture has come to a full rolling boil, set the timer for 2 minutes.

Insert a thermometer and cook the mixture until it reaches 230-234 F. Do not stir. (You have 2 minutes to reach this temperature, so adjust your heat up or down.)

Once the 2 minutes is up and you've reached the temperature between 230-234, remove from heat and quickly stir in peanut butter and vanilla extract, if using.

Once incorporated, quickly stir in the oats just until combined.

Next, stir in 1-2 tablespoons of milk until the mixture is creamy.

Using a mini cookie scoop, drop two scoops per cookie onto the prepared pans.

Allow the cookies to sit until room temperature and set, (about 30-45 minutes)

Store completely cooled cookies wrapped individually in plastic wrap and placed in an airtight container. The taste gets even better the n next day!