Place the unwrapped peanut butter cups on a plate.
Twist the Oreo sandwich cookie to separate it into two rounds, then use a butter knife to remove all the vanilla filling.
Break the two rounds of Oreo into equal halves to create the bat wings. Add ¼ of the vanilla filling at one tip of each bat wing.
Press the bat wing with the filling at an angle on one side of the peanut butter cup and another bat wing on the opposite side.
Add a dot of vanilla filling on the flat side of the candy eyes and press below the tips of the angled bat wings. Do the same for the remaining peanut butter cup, Oreo cookie, and candy eyes.
Chill for later or snack away.
Notes
If the weather is hot (greater than 80°F/27°C), chill the Reese’s cups for 15 minutes before attaching the Oreo cookies and candy eyes. Chill for at least 15 minutes after preparing them, if needed.If the weather is hot or humid, remove the filling immediately and break the Oreo cookies when you open the package. In hot or humid weather, the Oreo cookies will soften within a few minutes after opening.