Line an 9x9 baking pan with foil, then grease with baking spray.
Unwrap Reeses and place in a large ziploc freezer bag. Seal and smash peanut butter cups with rolling pin; set aside.
Place sugar, butter, and evaporated milk in a large heavy saucepan. Bring to full rolling boil on medium heat, stirring constantly.
Keep at a boil, stirring for 4-6 minutes or until candy thermometer reaches 234°. When the mixture has reached the ‘soft ball’ stage, take it off the heat.
Add peanut butter and marshmallow creme; stir until completely melted. Add vanilla; mix well.
Pour immediately into prepared pan; spread to form even layer in pan.
Cover with crushed peanut butter cups.
Let stand at room temperature 4 hours or until completely cooled.
To serve, lift from the pan; remove the foil and cut into 3/4 inch squares.