Preheat your oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan or line it with parchment paper for easy removal. In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, beat the softened butter and granulated sugar using an electric mixer on medium speed until the mixture becomes light and fluffy, about 4-5 minutes.
Add the eggs, one at a time, ensuring each egg is fully incorporated before adding the next. Stir in the vanilla extract.
Add the sour cream (both the 1 cup and the 1/4 cup) to the butter-sugar mixture, mixing until smooth. Gradually add the flour mixture in three parts, alternating with the whole milk, beginning and ending with the flour mixture. Mix until just combined.
Gently fold in the mini chocolate chips using a spatula, ensuring they are evenly distributed throughout the batter.
Pour the batter into the prepared loaf pan and smooth the top with a spatula. Bake for 55-60 minutes or until a toothpick inserted into the center comes out clean. If the top begins to brown too quickly, tent the cake with aluminum foil.
Let the loaf cool in the pan for 10 minutes, then transfer to a cooling rack to cool completely before slicing and serving. Enjoy your homemade chocolate chip loaf cake!