Preheat the oven to 400 degrees F. and grease a 12-cup muffin tin with or line with parchment liners.
Place 1 cup of the pistachios in the bowl in a food processor and pulse 2-3 times until they have a flour consistency. Be careful not to overprocess, or you'll end up with pistachio butter. Sift the pistachio flour into a small bowl. Chop the remaining ½ cup of pistachios and set aside (I use a mini food processor for this, or finely chop by hand). *see notes for the optional toasting step.
In a large bowl, whisk together the pistachio flour, all-purpose flour, baking powder, baking soda, and salt.
In a separate bowl, whisk together the eggs, milk, Greek yogurt, maple sugar, butter, and vanilla extract.
Add the wet mixture to the dry mixture and stir together with a few light strokes until just blended. Add the chopped pistachios and stir until just combined. Do not overmix.
Divide the batter, evenly, among the 12 lined muffin cups and sprinkle with a pinch of turbinado sugar, if desired.
Bake for 15 minutes, until a toothpick inserted into the center comes out clean. Cool for 2-3 minutes before removing from the pan onto a cooling rack.
Serve with softened butter, jam, honey, or a drizzle of melted chocolate, and enjoy.