I absolutely love key lime pie! I figured why not a key lime cake. This sponge cake is so light and tender, very similar to the carb loaded version. I used my Baking Mix, vanilla flavored whey protein and powdered Xylitol for this recipe. This I recently purchased my first bag of Xylitol, despite the tummy bloating it is said to cause. The difference between it and Erythritol is the cooling effect is less noticable with Xylitol and it costs quite a bit less than Erythritol. Both are natural sugar substitutes but Xylitol is sweeter and tastes more like real sugar in my opinion. So far my tummy doesn't see any difference either. I think this will be my new go to sweetener.
Combine the Baking Mix, whey protein, gluten and all-purpose flour in a small bowl and set aside. In a large mixing bowl beat egg yolks on high speed for 5 minutes until thickened and pale yellow. Stir in the lime juice, water, glycerin and lime zest and mix well. Slowly add the 1 cup of sweetener while beating on slow speed. Increase the speed to medium and beat until thickened and fluffy. Gradually fold in the flour mixture a little at a time until combined. Using clean dry beaters, beat the egg whites and cream of tartar or lime juice until soft peaks form. Gradually add the 1/2 cup of sweetener while beating on low speed, and then increase the speed to high and beat until stiff peaks form. Gently fold the egg whites into the egg yolk and flour mixture one cup at a time until smooth. Pour the batter into an ungreased tube pan. Bake in a 325 degree oven for 55-60 minutes until the cake springs back when gently pressed. As soon as you remove the cake from the oven invert the pan upside down onto a cooling rack. Completely cool in this position. Loosen the sides of the cake with a flexible rubber spatula and gently remove it from the pan. Top this cake with fresh berries and whipped cream, or a lime glaze.
To make the lime glaze, stir together 1/2 cup of powdered sugar substitute and 1/4 tsp guar gum, stir in 1/2 tsp lime juice, 1 tsp of butter, 2 tsp heavy cream and food coloring. Heat in the microwave for 20-30 seconds to dissolve sugar substitute, stir and cool in the fridge to thicken slightly. If it appears too thick, add a small amount of cream until you reach your desired consistency. Top the cake and Enjoy!