Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners or grease it lightly.
In a medium bowl, whisk together the 1 1/4 cup cake flour, finely ground 1 cup pistachios, 3/4 cup granulated sugar, 1 tsp baking powder, 1/4 tsp baking soda, and 2 tsp salt until well combined.
1 cup pistachios, 1 1/4 cup cake flour, 1 tsp baking powder, 1/4 tsp baking soda, 2 tsp salt, 3/4 cup granulated sugar
In another bowl, whisk together the 1 egg white, 1 egg, 1/4 cup sour cream, 1 tsp vanilla, 1 tsp almond extract, 1/2 cup whole milk, and melted 6 tbsp butter until smooth.
1 egg white, 1 egg, 1/4 cup sour cream, 1 tsp vanilla, 1 tsp almond extract, 1/2 cup whole milk, 6 tbsp butter
Pour the wet ingredients into the dry ingredients and mix until just combined. Do not overmix.
Divide the batter evenly among the muffin cups, filling each about two-thirds full.
Bake in the preheated oven for 15 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with just a few moist crumbs.
Allow the muffins to cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely.