Line two baking sheets with parchment and place them near the stove. Measure out the peanut butter, oats, vanilla powder, and salt before turning on the heat.
Combine butter, sugar, milk, and cocoa in a medium saucepan. Cook over medium heat, stirring until smooth, about 3 to 4 minutes.
Bring to a full rolling boil — wait until vigorous bubbles cover the entire surface — then boil for exactly 60 seconds, stirring gently. A thermometer reading of 230°F to 235°F is a useful checkpoint.
Remove the pan from the heat. Stir in peanut butter, vanilla powder, and salt until glossy. Add the oats and stir until every flake is coated and the mixture falls in heavy mounds.
Immediately scoop rounded 1 1/2-tablespoon mounds onto the parchment-lined trays. Work quickly as the mixture firms fast.
Let set at room temperature for about 30 minutes until cookies lift cleanly from the parchment.
