Line two baking sheets with parchment or wax paper.
Combine butter (or oil), sugar, milk, cocoa, and salt in a medium saucepan. Bring to a rolling boil and let it boil for 1 full minute, stirring constantly.
Remove from heat and stir in the peanut butter (or almond butter) and vanilla extract until smooth and fully combined.
Mix in oats and any optional add-ins like shredded coconut, espresso powder, or chopped nuts/chocolate chips.
Drop spoonfuls of the mixture onto the parchment-lined sheets.
Let the cookies rest at room temperature for 30-40 minutes, or in the fridge for 15-20 minutes, until set.