Prepare the Dough: In a large bowl, mix together softened butter, brown sugar, and white sugar. Add egg, water, and vanilla, and mix until fully combined.
Mix Dry Ingredients: In a separate bowl, whisk together flour, salt, cinnamon, and baking soda. Slowly add to the wet ingredients and mix until just combined. Fold in oats and chocolate chips.
Scoop and Shape: Using a 2-inch cookie scoop, place dough on a parchment-lined baking sheet, spacing cookies 2 inches apart. Flatten each cookie slightly with a spoon or fingers.
Bake: Preheat oven to 350°F (175°C). Bake for 12-15 minutes, or until edges are golden and centers are soft. (13 minutes works best in my oven).
Cool and Enjoy: Let cookies cool on the sheet for 5 minutes, then transfer to a wire rack. Allow to cool completely for at least 30 minutes for the perfect chewy texture. Enjoy with milk!