Preheat your oven to 350°F (175°C) and line a muffin tin with baking cups.
In a large bowl, combine the gluten-free flour, baking powder, ground cinnamon, and salt. Mix well.
In a separate bowl, whisk together the eggs, grated apple, stevia, melted coconut oil, lime zest, and vanilla extract until well combined. Stir in the grated zucchini.
Pour the wet ingredients into the dry ingredients and stir just until combined.
Evenly divide the batter into the prepared muffin tin, filling each cup about 2/3 full.
Sprinkle a pinch of ground cinnamon on top of each muffin for added flavor.
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Let the muffins cool in the pan for a few minutes, then transfer them to a wire rack to cool completely.