Place orange in a saucepan. Cover with water and bring to a boil. Reduce heat to low and simmer until orange is soft, about 30 minutes. Drain.

Cut orange into chunks and discard seeds.

Mix almond flour with 2 tablespoons sugar.

Preheat the oven to 350 degrees F (175 degrees C). Grease an 8-inch cake pan and coat the pan with a handful of the almond-sugar mixture.

Combine orange chunks and 1 cup sugar in a food processor; pulse until pureed. Add almond flour mixture and butter; process until smooth. Add eggs; mix until smooth. Add flour, baking powder, baking soda, and salt; process until just combined. Pour batter into the prepared cake pan.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 35 to 45 minutes.