Heat oven to 350 degrees. Prepare a 9x13 baking dish and spray with cooking spray or line with parchment paper.
In a small mixing bowl, combine the flour, cinnamon pumpkin pie spices, baking soda, and salt. Stir with a wire whisk to break up clumps.
In a bowl of a stand mixer, or a mixing bowl with a handheld blender, cream together the butter, granulated sugar, and brown sugar. Once fluffy and combined, add the egg and vanilla extract. Blend together. Add the pumpkin and beat together until combined together.
Add the dry ingredients into the wet mixture and beat on low speed just until combined. Add the chocolate chips and mix together.
Spread the pumpkin cake batter into the prepared pan. It's a thick batter so you may have to use the back of a spoon to spread it. It helps if you drop it all over the dish instead of just one big pile in the middle.
Prepare the streusel topping: Mix flour, quick oats, brown sugar, and cinnamon in a small bowl. Add the small cubed cold butter and use your hands or a pastry cutter to blend it until it resembles coarse, wet sand. This takes about 2-3 minutes to do, so don't be alarmed if it does not happen right away. The mixture should "look wet" (but it won't be wet, it will be more crumbly) and be combined.
Cook for 35-40 minutes. Mine was done at 35 minutes. You need to stick a toothpick in the middle to see if it's done. A toothpick inserted in the middle should come out with moist crumbs on it. Not wet batter!
Let cool in pan for 1 hour so it's easy to cut into clean slices. Keep leftovers covered at room temperature. The fridge tends to dry this out because of the streusel.