Combine dry ingredients (flour, oats, sugar, salt) with softened butter, then add water with dissolved baking soda. Gently mix in the mini chocolate chips.
Mold into a dough ball on the cooking sheet, then press it out into a square shape. Roll it out with a dough pin to make it about 1/4 inch thick. Shape the edges with a butter knife.
Cover and chill for 10-15 minutes to firm up the dough, then remove and score down the middle and across to make 8-10 squares (you'll use these lines for clean cuts after it's done baking).