Preheat your oven to 350°F (175°C).
In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, combine the melted butter, milk, eggs, and vanilla extract.
Pour the wet mixture into the dry ingredients and gently stir until just combined.
Fold in the white chocolate chips and chopped pistachios.
Grease a muffin tin or line with paper liners.
Spoon the batter into the muffin cups, filling each about two-thirds full.
Bake for 18-20 minutes, or until golden brown and a toothpick comes out clean except for melted chocolate.
Remove from the oven and let cool for a few minutes before transferring to a wire rack.
Serve warm for that molten lava effect and enjoy!
