Cream butter and sugars until light and fluffy, about 1-2 minutes. Add egg and vanilla beating until well combined. Slowly add flour, oats, salt, baking soda and chocolate chunks until just combined. With a large cookie scoop, scoop dough onto prepared baking sheet 2 inches apart. Bake for 14-15 minutes, until golden brown around edges. Remove and let cool on baking sheet for 10 minutes before removing. Serve warm or room temperature.