In a medium saucepan over low heat, stir together 1 cup creamy peanut butter and ½ cup unsalted butter until melted and smooth, about 2 minutes.
1 cup creamy peanut butter, 0.5 cup unsalted butter
Remove from heat, then whisk in 2 cups powdered sugar and 1 teaspoon vanilla extract until fully combined and glossy.
2 cups powdered sugar, 1 teaspoon vanilla extract
Fold in 3 cups Rice Krispies cereal until every flake is coated and the mixture holds together.
3 cups Rice Krispies cereal
Let cool 5 minutes on the counter so it’s easier to handle without sticking.
Use a 1-tablespoon scoop to shape into balls, placing them on a parchment-lined tray.
Chill in the refrigerator until firm, about 30 minutes, before serving.