Prep and preheat:
Preheat oven to 425°F and line a 12-cup muffin tin with paper liners or lightly grease.
Melt the butter:
In a small saucepan, melt the butter. If you would like to use brown butter, melt 10 tablespoons over medium heat until it foams, turns golden brown and, smells nutty, about 5–7 minutes. Immediately pour into a large mixing bowl to cool slightly.
Grind the pistachios:
Add the pistachios to a food processor and pulse until finely ground. Reserve 2 tablespoons for the streusel topping. Add the remaining pistachios to the melted butter and stir to combine.
Make the streusel:
In a small bowl, mix together the flour, sugar, salt, and reserved ground pistachios. Add butter and mix with a fork until crumbly. Set aside.
Mix the muffin batter:
To the bowl with the pistachio butter, whisk in sugar, eggs, Greek yogurt, vanilla, and almond extract until smooth. Sprinkle the flour, baking powder, baking soda, and salt on top. Stir until just combined.
Fill and top:
Divide batter evenly into the prepared muffin tin. Spoon streusel topping over each muffin. If you want that bakery-style dome, use a round cutter or mason jar ring to keep the streusel centered on top as they bake.
Bake:
Bake at 425°F for 5 minutes, then reduce oven temperature to 350°F and continue baking for 18–22 minutes, or until the tops are golden and a toothpick comes out clean.
Cool:
Let muffins cool in the tin for 5 minutes before transferring to a wire rack to cool completely.