Preheat the oven to 395°F (200°C). Butter a mini muffin pan and set aside.
Put the unsalted butter in a small pan over low heat. Swirl the pan regularly and peek at the color through the foam. When the milk solids turn brown at the bottom of the pan, take the pan off the heat and set aside to cool.
In a bowl, whisk together the granulated sugar, ground pistachios, almond flour, and cake flour. Whisk in the honey and egg whites. When combined, whisk in the cooled browned butter and mix until combined.
Divide the batter evenly among 12 wells and top with some chopped pistachios.
Bake for about 10 minutes or until you insert a toothpick and it comes out clean. Let them cool in the pan for a few minutes and pop them out onto a wire rack to cool completely.