Mix together flour, oats, brown sugar, soda, salt, and melted butter in a mixing bowl till crumbly.
Spread half of the dough in a well greased 9x13" pan. (For easier cutting and cleanup, line the pan with foil first.)
Bake at 350° for 8 minutes.
Meanwhile, stir together caramel and flour.
Remove crust from oven and sprinkle with chocolate chips and nuts. Drizzle caramel mixture evenly over the top. Crumble the remaining dough over the top of the caramel. It's OK if some of the filling is showing.
Return to the oven and bake for 20-25 more minutes or till golden brown and bubbly. Cool before cutting.
Notes
The original recipe called for 1 1/2 cups butter. I always thought they were a bit greasy, so I cut it down a bit. First I tried 1 cup, but they were dry. With the 1 1/4 cup, they taste just as rich and buttery, but aren't as greasy.