Line a large plate with parchment paper.
Stir sugar, peanut butter, cream cheese, chopped peanuts, and vanilla in bowl until uniform.
Roll mixture into twenty 1/2 inch balls; space balls evenly apart on prepared plate. Freeze, uncovered, for 15 minutes.
Microwave chocolate and oil in bowl, covered, at 50 percent power, stirring occasionally, until smooth, 2-4 minutes.
Using a fork, pick up 1 ball and dip in chocolate to coat, letting excess chocolate drip back into bowl.
Return ball to plate, and immediately place peanut half on top. Repeat with remaining balls.
Freeze balls uncovered, until chocolate has hardened, about 10 minutes.