Preheat the oven to 350 degrees Fahrenheit. Grease a large casserole dish or huge cast iron skillet.
In a small bowl, sift together cassava OR coconut flour and baking soda. Set aside.
Place the following ingredients into blender: eggs, cream cheese, sea salt, onion and garlic powder, and white pepper. Blend until mostly smooth, 10-15 seconds.
Add cheddar cheese cubes, flour mixture, melted fat and cream. (We have a Blendtec blender and this quantity fits perfectly in the jar, for blending. But it is fairly full.) Blend again, briefly, about 8 seconds, until all ingredients are fully incorporated and the cheese cubes have been reduced to bits, but are not fully pureed.
Pour creamy custard into greased casserole dish. Evenly distribute chopped artichoke hearts over its surface. Do the same with feta crumbles.
Bake until edges are golden brown and center is just set but still moist, 40 minutes. Allow to rest 10 minutes before serving.