Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.
In another bowl, beat the eggs lightly, then add the buttermilk, vegetable oil, and vanilla extract. Mix until thoroughly combined.
Pour the wet ingredient mixture into the dry ingredients and stir gently until just combined. Be careful not to overmix; it’s okay if there are a few lumps.
Fold in the semi-sweet chocolate chips, dark chocolate chips, and white chocolate chips until evenly distributed through the batter.
Using a spoon or a scoop, divide the batter evenly among the prepared muffin cups, filling each about ¾ full.
Bake in the preheated oven for about 18-20 minutes, or until a toothpick inserted in the center 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.
Notes
Arrange the muffins on a decorative plate and dust with powdered sugar before serving. For an extra touch, drizzle some melted chocolate over the tops.