For the Rice Krispie Treats:

1. Grease a 9 x 13-inch baking dish liberally with cooking spray (alternatively, for thicker treats, you can use an 8 x 8-inch or 9 x 9-inch pan). Line the pan with parchment paper and liberally spray the paper as well.
2. These come together quickly, so it is best to have all the components prepped and ready to go before you begin.
3. Place a large pot over medium heat and add the butter.
4. Once the butter is melted, add the 16-oz bag of mini marshmallows. Stir until the marshmallows are completely melted and then mix in the vanilla and salt.
5. Remove the pan from the heat and then stir in the cereal and chopped Oreos, mixing quickly while everything is still warm. Stir in the remaining 1½ cups of mini marshmallows.
6. Press the mixture evenly into the prepared baking pan. I find that using damp hands is the easiest way to do this.

For the Topping:

1. Combine the white chocolate chips and drizzle of oil in a microwave-safe bowl. Microwave for 20 seconds, stir well, and then repeat until the chocolate is completely melted and glossy.
2. Drizzle the melted chocolate all over the top of the treats and then sprinkle with the chopped Oreos while the chocolate is still warm.
3. Sprinkle over a little flaky sea salt, if desired. It’s totally optional but SO good if you enjoy the salty-sweet combo.
4. Allow the cereal treats to set for 1 hour. Remove from the pan and cut into squares.