1. Preheat your oven to 350°F or 175°C.

2. Grease a 9-inch or 23-centimeter round cake pan and set it aside for later use.

3. In a large bowl, whisk together 1 cup or 120 grams of almond flour and 1 cup or 200 grams of powdered sugar until well combined.

4. In a separate bowl, whisk 3 large egg whites until stiff peaks form. Add 1 tablespoon or 15 grams of grated orange zest and whisk until the zest is evenly distributed throughout the egg whites.

5. Gradually add 1 cup or 200 grams of granulated sugar to the egg mixture and continue whisking until the mixture becomes stiff and shiny.

6. Gently fold the egg mixture into the almond flour mixture until the two are well combined. Be careful not to overmix.

7. Pour the cake batter into the prepared cake pan and smooth the top to create an even surface.

8. Bake the cake for 25-30 minutes, or until a toothpick inserted into the center of the cake comes out clean.

9. Remove the cake from the oven and let it cool in the pan for 5 minutes before transferring it to a wire rack to cool completely.