Get out a large 10-inch pan with deep sides and heat the Butter (2 cup) in it over medium heat. Let it melt and then bubble until it turns golden brown and has a nutty smell. It burns quickly, so keep an eye on it. Let it cool for about 10 minutes or so.
Meanwhile, while it cooks and cools get out a stand mixer and set it up with the paddle attachment and also liberally grease a 9 x 13 pan with either more butter or cooking spray.
Meanwhile, get out a stand mixer and set it up with the paddle attachment. Add the Dark Brown Sugar (3/4 cup), Granulated Sugar (1/2 cup) and Vanilla Extract (1 teaspoon) to the stand mixer bowl. Combine the All-Purpose Flour (4 cup), Salt (1/2 teaspoon) and Ground Cinnamon (1/2 teaspoon) together in another bowl and whisk them together well.
Pour the cooled brown butter into the stand mixer bowl with the sugars and vanilla and beat them together thoroughly. Keep the pan you used for the brown butter though, don't put it in the sink. Then slowly pour in the dry ingredients and mix until you have a lovely dough.
Take 2/3 of the dough and press it firmly into the prepared baking dish to form a bottom crust, with it coming up the sides a bit to help hold the filling. Let the bottom crust chill for 20 minutes
While the dough chills, take the Walnut (1/2 cup) and beat them into the remaining dough and set it aside. This will be the top crust.
Preheat the oven to 375 degrees F (190 degrees C).
Bake the chilled bottom crust for 20 minutes until it is set and golden brown.
While it bakes, make the filling. Melt the Butter (4 tablespoon) in the same pan you used for the brown butter. Add the Gala Apples (6), Dark Brown Sugar (1/4 cup), Orange Juice (2 tablespoon) and Ground Cinnamon (1 teaspoon). Let it all gently simmer for about 15 minutes to bring out the flavors and cook off almost all of the liquid.
Reduce the oven heat to 350 degrees F (175 degrees C). Take the crust and spread the filling out evenly on it. Then take the remaining dough and crumble it evenly all over the top. It may not necessarily cover it completely. Bake the bars for about 25 to 30 minutes, until bubbly and completely golden brown on top.
Let them cool completely, then cut into 16 bars by making 3 even cuts horizontally and vertically. Serve and enjoy!!