01 - Preheat your oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup.
02 - In a large mixing bowl, thoroughly whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt until well combined.
03 - In a separate bowl, lightly beat the large eggs. Then, whisk in the whole milk, melted and cooled unsalted butter, and pure vanilla extract until smooth.
04 - Pour the wet ingredient mixture into the bowl containing the dry ingredients. Stir gently with a spatula until just combined. Be careful not to overmix, as this can result in tough muffins.
05 - Gently fold the semi-sweet chocolate chips into the batter. If desired, incorporate the optional chopped walnuts or pecans at this stage.
06 - Divide the prepared batter evenly among the 12 muffin cups, filling each approximately three-quarters full.
07 - Bake in the preheated oven for 18 to 20 minutes, or until a wooden toothpick inserted into the center of a muffin comes out clean or with only a few moist crumbs attached.
08 - Allow the muffins to cool in the muffin pan for 5 minutes before carefully transferring them to a wire rack to cool completely.