Raw flour can carry bacteria, so this step keeps the bites safe. Microwave the flour for 90 to 120 seconds, stirring every 30 seconds, until it hits 165°F (74°C). You can also bake it on a sheet pan at 350°F (177°C) for 5 minutes.
Warm flour will melt your butter and make the dough greasy. I spread mine out and let it cool fully before using it. If I am in a hurry, I pop it in the fridge and stir it once or twice.
Add the softened butter, brown sugar, and granulated sugar to your large bowl. Beat on high speed for 2 to 3 minutes. The mixture should turn pale, light, and fluffy.
Turn the mixer down to low speed. Pour in the vanilla and the milk. Mix just until everything looks smooth and well blended.
Add the cooled flour and the pinch of baking soda, if you use it. Mix on low until no dry streaks remain. The dough should feel soft, thick, and a little crumbly at first.
Pour in the mini chocolate chips. Use a spatula or wooden spoon to fold them through by hand. This keeps the chips whole and spread evenly.
Use a 1-inch scoop to portion the dough onto your parchment-lined tray. I like to roll each one between my palms for a smooth, round shape. You should get about 18 bites.
The dough is safe to eat right away. Still, the flavor is best after at least 1 hour in the fridge. Chilling also firms the bites, so they hold their shape.