Preheat oven to 350°F. Grease a 9x5 inch loaf pan with non-stick spray or line with parchment paper.
In a medium bowl, whisk together flour, baking soda, baking powder, and salt for about 30 seconds. Set aside.
In a large bowl, beat softened butter and sugar together on medium-high speed for 3-4 minutes until light and fluffy. Scrape down bowl sides occasionally.
Add eggs one at a time, beating well after each addition. Add vanilla extract and beat for another 30 seconds.
Add half the flour mixture and stir gently until barely combined. Pour in half the buttermilk and stir until just incorporated.
Add remaining flour mixture and stir carefully. Then add the rest of the buttermilk. Mix until everything just comes together with no dry flour visible. Do not overmix - a few small lumps are fine.
Fold in mini chocolate chips with a rubber spatula using 8-10 gentle folds from bottom to top. Reserve a few chips to sprinkle on top if desired.
Spoon batter into prepared loaf pan, spreading evenly and paying attention to corners. Smooth the top and tap pan gently on counter to release air bubbles.
Bake for 45-50 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter). Top should be golden brown and spring back when pressed.
Let cool in pan for 10 minutes. Run a knife around edges, then flip onto a cooling rack. Cool completely for at least 30 minutes before slicing.
Slice with a sharp serrated knife using a gentle sawing motion. Cut 1-inch thick slices. Serve plain, toasted, or with butter.