In a medium mixing bowl, whisk together the flour blend, baking soda, xanthin gum, and salt.
In a large mixing bowl, mix the melted butter and the sugars until smooth. Add the egg, milk and vanilla and stir until smooth. Add the flour mixture and mix until completely incorporated. Fold in the chocolate chips. Cover the bowl with plastic wrap and let rest for 30 minutes.
Meanwhile, preheat the oven to 350 degrees F. Line two baking sheets with parchment paper.
Working with two soup spoons, portion out the dough (about 1 1/2 tablespoons per cookie) and space the cookies 2 inches apart. You should have 12 per sheet.
Bake the cookies until golden brown. The edges will have begun to set, but the centers should still be soft, about 12 to 14 minutes. Rotate the sheets halfway through baking and swap from top to bottom.
Let the cookies cool on the sheet. Then serve alongside milk, or store for later!