Preheat your oven to 350°F.
Line a 9x13 inch baking dish with parchment paper, leaving some overhang on the sides for easy removal.
To make the crust, mix the flour, oats, baking soda, and salt in a small bowl.
In a large bowl, beat the butter and sugars together on medium speed for about 1 minute.
Scrape down the sides of the bowl, then gradually fold in the dry ingredients until the mixture forms a moist, crumbly texture.
Press half of this mixture evenly into the bottom of the prepared baking dish. Reserve the remaining half for the topping.
Bake the crust for 14 minutes.
While the crust bakes, prepare the filling. Beat the cream cheese in a large bowl on medium speed for 1 minute. Add the sweetened condensed milk, egg yolk, vanilla, and pumpkin pie spice. Continue mixing until well combined.
Once the crust is baked, spread the pumpkin cream cheese filling evenly over it.
Drop spoonfuls of pumpkin puree over the filling and use a spoon to swirl it in gently.
Sprinkle the reserved oat and sugar crumble mixture over the top. Bake for an additional 23 minutes.
Let the bars cool completely in the pan before cutting to ensure neat slices.