Line a rimmed baking sheet with parchment paper and set aside.

Add the butter to a large pot or saucepan and melt over medium heat, stirring as needed.

When the butter has fully melted, add the sugar alternative, peanut butter, and milk to the pot.

Stir continuously over medium heat until the mixture is smooth, glossy, and the sugar alternative has dissolved.

Remove the pot from the heat and immediately whisk in the unsweetened cocoa powder until fully incorporated and no dry streaks remain.

Add the oats to the pot and gently fold with a spatula until all of the oats are evenly coated in the chocolate mixture.

Working fairly quickly, use a cookie scoop or large spoon to drop spoonfuls of the mixture onto the prepared baking sheet, spacing them slightly apart.

If desired, lightly flatten the tops with the back of the spoon for flatter, bakery-style cookies.

Transfer the baking sheet to the refrigerator and chill for about 45 minutes, or until the cookies are firm to the touch.

Serve cold or at room temperature, and store any leftovers in an airtight container in the refrigerator.