Heat oven to 350°F (325°F if using a glass dish) and spray a 9x13-inch baking pan with nonstick spray.
For the Crust:
In the bowl of a food processor, add the flour, sugar, and salts. Pulse 3 times to combine the ingredients.
Add the cold butter and pulse until the mixture is crumbly and the butter is just smaller than pea size.
Pour the flour/butter mixture into the prepared dish and press firmly down, being sure to get corners and edges.
Bake the crust 15 minutes and transfer from the oven.
For the Pecan Pie Topping:
While the crust is cooking, prepare the pecan pie topping.
In a medium bowl, beat together milk, egg and vanilla.
Stir in the chips and pecans; set aside until crust is ready.
When the crust is ready, give the pecan mixture a couple of stirs and slowly spread it evenly over the crust.
Bake the bars at 350°F for 25 minutes or until golden brown and set in the middle.
Set the bars on a cooling rack to cool, and after 10 minutes, slide a sharp, thin knife between the pan and the bars to loosen the sides. Allow the bars to cool completely before cutting into bars.
Store Pecan Pie Bars in an airtight container in the fridge. They will keep up to 3 weeks.