In a large bowl, combine sugar and oil until smooth. Add the egg, milk, pumpkin puree, and vanilla extract. Stir until the mixture is well blended and creamy. This creates the moist base of the cookies.
In a separate bowl, mix together flour, cinnamon, salt, baking powder, and baking soda. Slowly add the dry ingredients to the wet mixture. Stir gently until just combined. Avoid overmixing to keep cookies soft.
Fold in the chocolate chips evenly throughout the dough. Drop spoonfuls onto a lined baking sheet, leaving space between each cookie. Bake at 375°F (190°C) for 10–12 minutes. The edges should be set while the centers remain soft. Let them cool before serving.