Preheat the oven to 350°F. Lightly grease a 9" x 13" pan., To make the crust: Combine the flour, oats, sugar, baking soda, and salt. Add the butter and stir by hand or on low speed of a stand mixer until the mixture is crumbly., Transfer half the crumb mixture to the prepared pan and press it evenly into the edges and corners., Bake the crust for 10 minutes., Remove the crust from the oven and set it aside to cool for 10 minutes., To make the filling: Melt the caramel and milk over low heat in a saucepan or in a microwave, stirring to combine., Pour the caramel onto the crust, spreading it to the edges, and allow to cool until set, about 20 to 30 minutes., Scatter the chocolate chips and pecans evenly over the firm caramel layer, then top with the remaining crumb mixture., Bake the bars for 25 to 30 minutes, until the crust is lightly browned and the caramel is bubbling around the edges., Remove the bars from the oven, loosen the edges, and allow them to cool completely in the pan before cutting and serving., Store wrapped bars at room temperature for a few days; freeze for longer storage.