Preheat your oven to 350 degrees and lightly grease a square 8×8 BAKING DISH or line with parchment paper.
Make the brown butter: Add the diced butter to a small skillet or pot. Heat the skillet to medium heat. The butter will start to melt as the skillet heats up. Allow the butter to bubble and “cook” until it begins to change from a bright yellow color to a golden brown color. Continually stir the butter as you see the foam start to dissipate and brown bits begin to form in the bottom of the pan. Cook and stir the butter until it is a golden brown color and has a nutty aroma. Remove the butter from the heat and transfer to a heat safe dish to let cool.
Make the Cinnamon Orange Layer: Add the dark brown sugar, all purpose flour, ground cinnamon, and orange zest to a small bowl and stir until well combined.
Make the Streusel Topping: Add the melted butter, brown sugar, all purpose flour, cinnamon, and salt to a small mixing bowl. Stir together until well combined and a crumble forms. Set aside.
Make the Coffee Cake Batter: Add the melted and cooled brown butter, Greek yogurt, vanilla extract, granulated sugar, and almond milk to a large mixing bowl. Whisk together until well combined.
To another mixing bowl, add the all purpose flour, salt, baking powder, and baking soda. Whisk together until well combined.
Gently fold the dry ingredients into the wet ingredients until you have a thick batter.
Assemble the Coffee Cake and Bake: Transfer half the batter into the prepared baking dish and spread in an even layer. Next, sprinkle the cinnamon orange layer even over the batter. Next, pour the remaining batter over the cinnamon layer and smooth into an even layer.
Next, sprinkle the streusel topping evenly over the coffee cake.
Bake the coffee cake at 350 degrees for 30-40 minutes or until a toothpick comes out clean when inserted into the middle of the cake. If using a ceramic baking dish the cake may take a bit longer to bake.
Make the Vanilla Orange Icing: Add the confectioner’s sugar, orange juice, vanilla extract, and orange zest to a mixing bowl. Whisk together until well combined and smooth.
Let the coffee cake cool for 15-20 minutes before drizzling the icing over the cake while warm. Slice into 9 squares and enjoy!