It's a Toffee Job, but Somebody's Got to Do It!

I have officially started my second year of residency, which means I am an upper level.  I lead the team, have to see all of our patients, and help the interns make decisions about patients overnight (if they need help).  I definitely have to get used to is because some of my responsibilities have changed from those I had last year.  I have survived the first call, which all in all wasn't too bad, though I think we admitted more than any team over the 4 day stretch.  I made some cookies, as per usual, but didn't take a picture.  I'm trying to re-create a cookie (that I have never tasted, BTW) for one of my mom's friend.  A chocolate and pecan cookie that is "chewy" and has "air pockets" in it...they apparently used to make it at MSU in the 70's but don't anymore!  Anyway, I took the first version of this cookie, and though good, I don't think it was "the" cookie.  I'll keep trying.  Any suggestions on reaching these goals?!

Anyway, I made this snack cake for a call many months ago.  The inspiration was a toffee snack cake that Peabody made.  I LOVE toffee...and to me, adding banana in with it is just perfect.  I've done it before in a nice, light summer pie and the results are great; so why not try in a cake.  I had a banana left over and decided to add that to these bars.  The results were great.  A not too banana flavored cake that remained moist and had a little crunch from the toffee!  Yum!

Banana Toffee Cake
1/4 cup unsalted butter, at room temperature (Peabody used 1/2 cup...use that if you like!)
1 ripe banana, mashed
  3/4 cup dark brown sugar, packed (I decreased this slightly, maybe even more than noted here, due to the sweetness from the banana)
1 egg
1 tsp vanilla extract
1 ¼ cup self rising flour
¼ cup yogurt
¼ cup buttermilk
1 ½ cups toffee pieces, divided
Preheat oven to 350F.

Spray a 8-x-8-inch pan with baking spray. Set aside.
Using a stand mixer, cream together the butter, banana, and brown sugar on medium speed until light and fluffy, about 3 minutes.
Add the egg and vanilla extract and beat until incorporated.
In a small bowl whisk together the buttermilk and sour cream.
Turn mixer speed to low. Starting with the flour alternate flour and buttermilk mixture ending with flour. Fold in ½ cup toffee pieces.
Pour into prepared pan and bake for 25-30 minutes. Insert a knife or wooden skewer to test for doneness.
Remove from oven. Sprinkle the remaining 1 cup toffee pieces on top.Store in an air tight container.  Enjoy!