Preheat your oven to 180°C (350°F) and line a muffin tin with paper liners or grease it well.
In a large bowl, whisk together the flour, brown sugar, and baking soda until evenly combined. This creates a light, airy dry mixture.
In a separate bowl, melt the butter until just warm, then whisk in the eggs one at a time, followed by the buttermilk and vanilla. Whisk until the mixture is smooth and fragrant.
Pour the wet ingredients into the dry mixture and gently fold with a spatula or spoon until just combined. Be careful not to overmix; some lumps are okay.
Gently fold in the chocolate chips, distributing them evenly throughout the batter. This ensures a good chocolate-to-batter ratio and prevents sinking.
Spoon the batter into the prepared muffin cups, filling each about 3/4 full. Tap the tin lightly on the counter to settle the batter and remove air bubbles.
Bake in the preheated oven for 20-22 minutes, or until the muffins are golden on top and a toothpick inserted into the center comes out clean.
Remove the muffins from the oven and let them rest in the tin for 5 minutes. This helps them set and makes removal easier.
Transfer the muffins to a cooling rack and cool for a few more minutes, or enjoy warm for a gooey, chocolatey treat.
Serve the muffins warm or at room temperature, layered with butter, nut butters, or enjoyed plain. These are best eaten within 2 days for optimal freshness.
