Preheat the oven to 375 degrees F. Line a 9x13-inch baking pan with parchment paper, letting some overhang on the long sides.

Combine cranberries, orange zest, orange juice, 6 tablespoons coconut sugar, arrowroot flour, almond extract, and cinnamon in a small bowl; stir well. Set aside.

Whisk almond flour, oat flour, oats, salt, nutmeg, and orange zest together in a large bowl. Add in the melted butter, pure maple syrup, and vanilla extract and stir until a nice crumble forms and mixture begins to clump together.

Reserve 1 cup of the mixture for the topping and set aside. Use your hands to evenly press the remaining dough into the bottom of the pan to form the crust.

To assemble and bake: Give the cranberry mixture a quick stir, then pour it over the crust, spreading evenly. Sprinkle the reserved crust mixture on top. Pressing crumble gently into cranberries.

Bake until the top is lightly browned, about 40 minutes. Transfer to a wire rack and let the bars cool in the pan for 15 minutes. Lift the long sides of the parchment to remove and place on a cutting board. Use a sharp knife to cut into 15 bars. Cool completely. Garnish with powdered sugar or Monk Fruit sugar before serving, if desired.