Preheat your oven to 350°F (175°C) and prepare an 8x8-inch baking pan by greasing it or lining it with parchment paper.
In a large mixing bowl, combine rolled oats, almond flour, coconut sugar, ground cinnamon, and salt. Mix thoroughly.
In a separate bowl, whisk together melted coconut oil, maple syrup, and vanilla extract. Fold in diced apples and optional ingredients if using.
Pour the wet mixture into the dry ingredients and stir until well combined. Spread the mixture evenly in the prepared baking pan and press down firmly.
Bake in the preheated oven for 25-30 minutes until the edges are golden brown and the center is set. Let cool for 10 minutes before transferring to a wire rack.