Step 1

Line a 9x13-inch pan with wax or parchment paper and grease well.

Step 2

Heat a large skillet or saucepan over low heat. Add the marshmallows, cake mix, and vanilla.

Step 3

Stir frequently as the marshmallows melt until the mixture is smooth. Quickly fold in the rice krispies to the marshmallow mixture until combined and everything is coated.

Step 4

Transfer sticky cereal mixture to the prepared pan, pressing down with the back of a greased spoon or your fingers until the top is level.

Step 5

Allow the krispie treats to set, at least 15 minutes before cutting and serving.

Step 6

Drizzle white chocolate over the top, if desired.