1 (12-ounce) box Rice Chex cereal (about 11 cups)
1 1/2 cups semisweet chocolate chips (10 ounces)
3/4 cup smooth peanut butter, such as Skippy
6 tablespoons (3/4 stick) unsalted butter
1/4 to 1/2 teaspoon kosher salt
1 1/2 teaspoons vanilla extract
2 1/2 cups powdered sugar, divided
Pour cereal into a large mixing bowl.
Place the chocolate chips, peanut butter, butter, and salt in a medium microwave-safe bowl. Microwave on high for 1 minute. Stir, then continue microwaving in 15 second intervals, stirring in between each, until almost melted, about 45 seconds more. Remove from the microwave and stir until smooth. Stir in the vanilla.
Pour the chocolate peanut butter mixture over the cereal and toss until all the cereal is evenly coated.
Place 1 cup of the powdered sugar in the bowl, mix gently, then add the rest of the powdered sugar. Shake vigorously until the cereal is evenly coated.