Preheat oven to 350F. Grease a 9x13-inch baking pan.
In a large bowl, combine 2 cups flour, oats, brown sugar, baking soda and salt. Cut the butter into cubes, then cut into the flour mixture until crumbly. -Or- use a food processor to mix well to evenly distribute the butter throughout the flour mixture.
2 ¼ cups flour, 2 cups oatmeal, 1 ½ cups brown sugar, 1 teaspoon baking soda, ½ teaspoon salt, 1 cup butter
Set half the mixture aside for the topping, then press the rest into the greased 9x13 pan. Bake for 15 minutes.
Sprinkle the hot crust with the chocolate chips and chopped pecans.
2 cups chocolate chips, 1 cup pecans
In a bowl, whisk the caramel sauce and ¼ cup flour together until smooth. Drizzle evenly over the chocolate and nuts.
12 ounces caramel sauce
Sprinkle the reserved crumb mixture over the chocolate-caramel layer. Bake for 18-20 minutes or until lightly golden brown. Cool on a wire rack for at least 2 hours before cutting.