Old fashioned peanut butter cookies
Did you substitute natural ground peanut butter for the peanut butter ingredient? The popular peanut butters in a jar have stabilizing ingredients added to maintain texture at room temperature.
This is usually the telling problem with recipes that use PB as they were developed using this more coherent PB product.
,You may certainly use natural PB but adjustments need to be made in the recipe to balance the room temperature liquidity of the oilier PB by adding less milk or shorting the butter by a tablespoon or two.
Be wary of adding additional sugar beyond what the recipe states as sugar does function as a softening addition when it dissolves into the fats.
,The other suspect ingredient might be the oatmeal.
Did the recipe call for quick-cooking oatmeal or old-fashioned rolled oats? Quick-cooking will absorb liquid in a recipe much more quickly (read: stiffening the batter) than itu2019s larger flake version particularly when you are adding to a hot mixture.
They are not always interchangeable and no-cook cookies are not as forgiving with substitutes as baked cookies.