Lightly grease a 9x9-inch baking dish and line with parchment paper.

Melt the cacao butter in a small saucepan set over low heat, stirring often.

Mix all of the ingredients except for cacao butter and shelled pistachios with an electric mixer in a large bowl.

Pour the melted cacao butter into the almond mixture and resume mixing on low speed until well incorporated.

Transfer to prepared dish, spread as evenly as possible. Sprinkle with chopped pistachios.

Refrigerate until completely set, at least 4 hours but preferably overnight.

Cut into 36 squares and serve.