Place the pistachios and 2/3 cup sugar in a blender or food processor. Pulse until the pistachios are a fine powder. 2. Set aside.
Pistachio Muffin Batter
Preheat oven to 375 degrees. Line standard 12-cup muffin tins with paper liners. 2. Combine flour, almond flour, baking powder, and salt into a bowl. Set aside3. With an electric mixer on medium speed, cream together butter and granulated sugar until fluffy. 4. Add almond extract, eggs and egg yolks until well combined. 5. Reduce speed to low; alternate adding flour mixture and milk. 6. Gently fold in pistachios by hand. 7. Divide batter evenly among prepared cups; if desired, sprinkle generously with granulated sugar crumb topping. 8. Bake until light golden on top, about 30 minutes.
Whisk together flour, pistachio paste, brown sugar, and salt, in a bowl. 2. Pour in melted butter and toss with a flexible spatula until large crumbs form.3. Sprinkle with turbinado sugar if desired.