Line an 8-inch square baking pan with parchment paper, leaving some overhang on two sides. This makes lifting and slicing much easier.

In a large bowl, combine the crispy rice cereal, chopped nuts, and 1/2 cup dried cranberries.

Place 1 cup white chocolate chips and the butter or coconut oil in a microwave-safe bowl. Heat in 20 to 30 second intervals, stirring well between each interval, until smooth. Do not rush this step, because white chocolate burns easily.

Pour the melted white chocolate over the cereal mixture. Gently fold until everything is lightly coated. Work quickly but carefully so the chocolate does not firm up before pressing.

Transfer the mixture to the prepared pan. Use the back of a spoon or the bottom of a glass to press it into an even, compact layer. You want it firm but not crushed into a dense brick.

Refrigerate for 15 to 20 minutes while you prepare the next layer.

Heat 2 cups white chocolate chips with the heavy cream in short microwave intervals, stirring frequently, until smooth and glossy. Stir in the vanilla extract and a pinch of salt. If the mixture looks too thick, add a little more warm cream, one teaspoon at a time.

Pour the white chocolate mixture over the chilled base and spread it into an even layer.

While the white chocolate layer is still soft, scatter the dried cranberries, chopped nuts, and crispy rice cereal over the top. Press gently so the pieces stick.

Refrigerate for at least 2 hours, or until completely firm.

Lift the slab out using the parchment overhang, place it on a cutting board, and cut into squares or bars with a sharp knife.