01 - Preheat oven to 350°F. Grease and flour a 9-inch round or square cake pan.
02 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
03 - Beat butter and sugar in a large bowl until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Stir in vanilla extract.
05 - Gradually add dry ingredients to wet mixture, alternating with buttermilk. Begin and end with dry ingredients. Mix until just combined; avoid overmixing.
06 - Toss chocolate chips with 2 tablespoons flour, then gently fold into batter.
07 - Pour batter into prepared pan. Smooth top surface. Sprinkle with coarse sugar or additional chocolate chips if desired.
08 - Bake for 35–40 minutes until toothpick inserted in center emerges clean or with few moist crumbs.
09 - Cool in pan for 10 minutes, then transfer to wire rack to cool completely. Slice and serve.