Rocky Road Oatmeal Squares

This recipe came as one of those daily email subscriptions that I always rarely pay attention to (even though I intend to...).  Glad this one managed to get my attention--delicious and easy to make!  It's on the rich side, but not extremely.  You will want some milk to go with this bar cookie, be prepared!
Here is the link to original recipe:
http://www.cooking.com/recipes-and-more/recipes/rocky-road-oatmeal-squares-recipe#axzz3ksteUwok
I made it exactly as written except that I was 1/4 cup short on the old fashioned oats, so I subbed in some quick oats.  Think it turned out just fine :)

Ingredients:

--for the oatmeal cookie base--
1 1/2 c. old fashioned rolled oats
1 1/4 c. all-purpose flour
1/2 tsp. baking soda
1/2 tsp. salt
7 T. unsalted butter, softened, wrapper reserved
1/2 c. dark brown sugar
1/2 c. sugar
1 egg
1 tsp. vanilla extract

--for the filling--
1 T. unsalted butter
7 oz. (1/2 can) sweetened condensed milk
1 c. semi-sweet chocolate chips
1/2 tsp. salt
1 tsp. vanilla extract
1/2 c. mini marshmallows

--for the topping--
1/2 c. mini marshmallows
1/2 c. semi-sweet chocolate chips

Instructions:

1. Preheat oven to 350°F.

2. For the cookie base, begin by combining oats, flour, baking soda, and salt in a small bowl.  Set aside.

3. Use electric mixer to cream butter and both sugars until light and fluffy.

4. Add egg and vanilla, mix until fully incorporated.

5. Add dry ingredients, about a 1/3 at a time.  Finish by mixing by hand if needed.  Only mix until all ingredients are just incorporated.

6. Grease an 8"x8" pan (or 9"x9", like I used) using the reserved butter wrapper.  Press 2/3 of the cookie batter into the pan and reserve the rest.

7. For the filling, place butter, condensed milk, and chocolate chips in a microwave safe bowl.  Microwave for 30 seconds and then stir.  Microwave for additional 10 second increments until mixture becomes smooth when stirred (it only took 40 seconds total for mine).

8. Add salt, vanilla, and marshmallows.  Stir to incorporate.

9. Pour into baking dish and spread to top cookie base.

10. For the topping, use reserved cookie dough to dot all over top of filling (filling will still be visible after).

11. Sprinkle marshmallows and chocolate all over top.

12. Bake for 28-32 minutes (23-27 for 9"x9" pan), until marshmallows are nicely browned.

13. Let cool completely before cutting into squares to enjoy!