Preheat the oven to 350°.
For the crust, combine oil, eggs, brown sugar, salt, flour, oatmeal, and baking soda. Stir well. (It will be thick like cookie dough.)
Press half into a greased 9x13 inch baking dish, covering the bottom completely. Set the rest aside.
For the filling, in a medium saucepan, over medium heat, stir together the chocolate chips, sweetened condensed milk, and butter. Continue cooking and stirring constantly until melted.
Pour the filling over the crust. Top the filling with the remaining crust. (I press small handfuls of dough together to form blobs* * and drop them unevenly onto the top of the filling.)
Bake for 20-25 minutes until the crust is golden.