Preheat oven to 350 degrees.
Grease the bottom of a 9x13 baking dish and set aside.
Combine all ingredients, except pecans, in the bowl of a stand mixer.
Beat at low speed until mixture resembles coarse crumbs. Slowly, add in pecans and mix well.
Press mixture firmly down into baking dish. I sometimes like to use the bottom of a glass cup for this. B
Bake 15-20 minutes (mine took 18 minutes) or until edges are slightly brown. Make sure not to overcook it.
While crust is baking, make the filling. Combine all the filling ingredients into a bowl and mix well.
Pour filling mixture overtop of partially baked crust. Then, bake again for another 18-20 minutes.
Let bars cool completely to room temperature before starting on the frosting.
Once bars are cool, combine all the key lime frosting ingredients into a bowl, except for key lime peel. Beat until combined.
Spread key lime frosting over bars and then sprinkle with the freshly grated peel.
Cut into bars and enjoy!