Preheat the oven to 400 degrees Fahrenheit/ 200 degrees Celsius. Line the muffin tin with paper liners.
Melt butter in a small pan. Set aside to cool slightly while you mix the rest of the ingredients.
Dry ingredients: Whisk flour, baking powder, baking soda, sugar, and a pinch of salt in a large bowl.
Wet ingredients: Whisk buttermilk, red gel food coloring, eggs, vanilla extract, vinegar, and melted butter in a medium bowl.
Combine: Pour the wet ingredients over the flour mixture. Stir gently and shortly until just combined. Don’t over stir. Fold in chocolate chips.
Bake: Scoop the batter into the muffin tin cups and bake for about 20 minutes or until a toothpick inserted in the middle of a muffin comes out clean.
Rest for 5 minutes. Remove muffins and let cool on a wire rack. If desired, sprinkle with icing sugar before serving.