Preheat your oven to 350°F. Grease and line a 8-inch square cake pan and set it aside. You can also use a 9-inch round cake pan.
In a medium-size bowl, whisk together flour blend, xanthan gum, almond flour, baking powder, baking soda, and salt. Set the bowl aside.
In a 4-cup measuring cup or a separate medium size bowl, whisk the eggs, yogurt, milk, vanilla and optional butter emulsion oil until very smooth.
In a large mixing bowl, whisk the sugar with oil until the mixture creates an emulsion and becomes creamy and shiny, about 2 minutes.
Add the whisked dry ingredients to the sugar and oil mixture in 3 parts, alternating with the egg, yogurt and milk mixture in 2 parts, beginning and ending with the dry ingredients.
Use a spatula to mix in the last portion of the dry ingredients. Turn over the cake batter over by hand one last time to ensure that everything is well-combined. It should be thickly pourable and very smooth.
Transfer the cake batter to the prepared cake pan. Shake the pan gently back and forth to distribute the batter into an even layer. Bang the pan flat on the counter a few times to break any large air bubbles.
Bake the cake until it is starting to pull away from the sides of the pan, is lightly golden brown on top and a toothpick inserted into the center comes out clean (about 30 minutes).
Allow the cake to cool in the pan for 10 minutes before turning it out onto a wire rack to cool completely. Remove any paper lining so the cake can cool freely.
Frost and decorate as desired only after the cake is completely cool. Slice into 8 equal pieces and serve.
Notes
Flour blend information Be sure to use a dairy free flour blend with a superfine rice flour as a base, like Better Batter's classic blend (do not add additional xanthan gum), Bob's Red Mill 1-to-1 gluten free flour (add an additional 1/8 teaspoon xanthan gum since it doesn't have enough), or Vitacost multi-blend gluten free flour.Avoid Nicole's Best here because it has milk powder. You can also make my mock Better Batter blend. Almond flour Be sure you're using finely ground and sifted blanched almond flour with its skins removed, not almond meal, which has its skins intact and is more coarsely ground.