Pre-heat oven to 350° with rack in the center. Use a well sprayed 9-inch spring form pan or a deep 9-inch round cake pan. Line pan with a parchment bottom and collar, spray again. Set aside.
Zest the best parts of both oranges into bowl of stand mixer.
To supreme the oranges: Cut off top and bottom of both oranges. Peel the oranges and separate into segments, removing as much of the pith from sides and center. Use a small sharp knife to separate the membranes from the orange segment; slice the membrane along the center of the segment (trying not to pierce the orange), then peel off and discard. Put all the supremed oranges into a 2-cup measuring cup, squeeze the leftover skins for their juice into the measuring cup, to equal ¾ cup total.
Place the zest and oranges with juice into the bowl of a stand mixer. Using the paddle attachment, add the egg yolks, remaining ¼ tsp. salt, and ¾ cup sugar. Mix on low until combined. Add the Nut Flour Blend and vanilla and beat on medium high until pale, approx. 3 minutes.
In a separate bowl, whip egg whites and ¼ tsp salt to soft peaks. Slowly add ¼ cup of the sugar, and beat until firm, stiff peaks form.
Use a rubber spatula to gently fold the egg whites into the batter, fold until well blended (a couple minutes). Once combined, pour into prepared pan and bake for 40 to 45 minutes, until golden brown all across the top.
Let cool on a rack for 15 minutes or more before removing the spring form band. If in a cake pan with a collar, let cool in pan before removing. It is normal for this cake to sink in the center a bit.
Chill in refrigerator before cutting. Dust with powdered sugar or glaze before serving.
© Pamela's Products, Inc.