Gather your equipment: a medium saucepan, a spoon or spatula, parchment paper, and a baking sheet or flat surface for setting the cookies.
Combine butter, sugar, and cocoa powder in the saucepan, then place over medium heat. Stir gently as the mixture begins to melt, filling your kitchen with a rich chocolate aroma.
Bring the mixture to a gentle boil, stirring constantly. Let it bubble for about 1 minute until it’s shiny and slightly thickened, then remove from heat.
Stir in the vanilla extract, then quickly add the rolled oats. Mix vigorously to coat all the oats evenly with the chocolate mixture—this creates a thick, fudgy dough.
Once combined, use a spoon or cookie scoop to drop dollops of the mixture onto parchment-lined baking sheet. Slightly flatten each mound with the back of the spoon if you prefer a flatter cookie.
Allow the cookies to cool at room temperature for at least 30 minutes, giving them time to firm up and develop that chewy, fudgy texture.
Once set, enjoy these indulgent, nostalgic treats—perfect for sharing or savoring on your own. Store leftovers in an airtight container at room temperature for up to 3 days.
