Mix the Base: In a mixing bowl, combine ½ cup creamy peanut butter, 4 oz softened cream cheese, ½ tsp vanilla, and ½ tsp salt. Use a hand mixer or stand mixer to blend until the mixture is fluffy and well-combined.
Add Sugar: Gradually add 2 cups powdered sugar to the peanut butter mixture. Mix on a low setting to avoid a sugar cloud, and then increase the speed. Continue mixing until all the sugar is fully incorporated, and a soft dough forms.
Shape the Balls: With clean hands, scoop out portions of the dough and roll them into 1-inch balls. Place the formed balls onto a lined baking sheet. Chill them in the freezer for about 20 minutes to allow them to firm up.
Melt the Chocolate: In a microwave-safe bowl, combine 1½ cups dark chocolate chips and 1 tbsp vegetable oil. Heat in the microwave in 30-second intervals, stirring in between until the chocolate is smooth and fully melted.
Coat the Buckeyes: Remove the chilled peanut butter balls from the freezer. Using a toothpick, dip each ball into the melted chocolate, swirling to coat evenly. Allow the excess chocolate to drip back into the bowl.
Set the Treats: Place the chocolate-covered Buckeyes back onto the parchment-lined baking sheet. Once all are coated, remove the toothpicks. Smooth over any holes left by the toothpick with your finger or a spoon.
Freeze to Set: Return the Buckeyes to the freezer for at least 30 minutes or until the chocolate is fully set.