Heat oven to 350. Grease bottom and sides of 9x13 baking pan.
In large bowl, beat 2 cups of flour, the oats, brown sugar, baking soda, salt, and butter with electric mixer on low speed until crumbly. Press about 3 cups of mixture in prepared pan. Bake 10 minutes.
While bottom crust bakes, mix caramel topping and 3 Tbsp. flour together in a small bowl.
When crust comes out of the oven, sprinkle with apple and pecan pieces. Drizzle with caramel mixture. Sprinkle with remaining crust mixture.
Bake 25-30 minutes longer or until golden brown. Cool completely, about 1 hour. Cut into bars.
Recipe adapted from Betty Crocker: The Big Book of Cookies