Preheat oven to 350°F (175°C) and grease a 9x13 inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, combine the melted butter, white sugar, and brown sugar. Stir until well mixed and smooth.
Add the eggs and vanilla extract to the butter-sugar mixture, stirring until fully incorporated.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Fold in the mini chocolate chips, making sure they are evenly distributed throughout the dough.
Spread the dough evenly in the prepared 9x13 inch pan, smoothing the top with a spatula.
Bake for 25 to 30 minutes, or until the edges are golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.
Let the bars cool in the pan before cutting into squares and serving.