Prepare the Dry Ingredients: In a bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. Set aside.
Mix the Wet Ingredients: In a mixing bowl, cream the butter, coconut oil, maple syrup, and brown sugar until fluffy. Add the vanilla, egg, and egg yolk, mixing until combined. Slowly incorporate the dry ingredients until just mixed.
Make the Cinnamon Filling: In a small bowl, mix brown sugar, butter, and cinnamon until smooth.
Assemble the Cookies: Scoop 20 tablespoon-sized cookie dough balls onto a parchment-lined baking sheet. Place ½ teaspoon of cinnamon filling in the center of each. Top with another layer of dough and gently press down.
Chill the Dough: Freeze for at least 1 hour (or overnight) to prevent spreading and enhance the flavor.
Bake the Cookies: Preheat your oven to 350°F. Bake for 12-14 minutes, rotating the tray halfway through. Let them cool completely before frosting.
Make the Cinnamon Glaze: Whisk powdered sugar, cinnamon, and almond milk until smooth.
Frost the Cookies: Spread about 2 teaspoons of glaze over each cooled cookie, leaving a small border.
Let Them Set & Enjoy! Once the glaze sets, serve and enjoy!