Sweethearts Citrus Shortbread Cake

I made this for my wife for Valentines Day:

Cake Ingredients
2.25 cups GF baking mix (includes rich flour, sugar, baking powder, potato starch, salt, and xanthan gum)
2.75 cups coconut flour
3/4 tsp xanthan gum
3.25 tsp baking powder
3/4 tsp salt
1/2 cup wildflower honey (dry measure, not liquid)
1/2 cup concentrated monkfruit sugar (1/2 cup = 1 cup sugar)
1/4 cup sugar
1/2 cup unsweetened applesauce
1 tsp vanilla
1/3 cup coconut oil
1/3 cup other oil (vegetable, corn, safflower, etc.)
one 13.66 fl oz can unsweetened coconut milk
1 cup water
zest of two ugli fruit
zest of two meyer lemons
juice of two ugli fruit
juice of two meyer lemons

Preheat oven to 325 F.  Lightly spray two large loaf dishes (5.25 x 9 x 2.75) and one 9 x 9 baking dish with coconut oil.  In a large mixing bowl place dry ingredients and mix well.

Zest both ugli fruits and one meyer lemon into mixing bowl.  Zest other lemon into small mixing bowl.  Juice both ugli fruits into large liquid measure (yields 2 to 3 cups; nearly 2.5 cups for this batch).  Juice lemons into small liquid measure; the reason to juice separately is that meyer lemons tend to have more, and smaller, seeds, so this makes it easier to catch and remove them.  Place 1 tsp meyer lemon juice and 1 tbsp ugli fruit juice into smaller bowl with zest and set aside.

Mix wet ingredients into dry and blend well with hand mixer.  Place batter into dishes and spread out.  Place in oven, with 9 x 9 dish in center.  Bake 20 minutes, then drop heat to 300 and bake another 20-30 (until a toothpick stuck into center comes out clean).  The lower temperature is due to the use of honey, as it caramelizes and burns faster, and the extra liquids and baking powder are for the use of the coconut flour, which is highly absorbent.

For topping, move saved zest and juice into fresh (or newly washed) large mixing bowl, then added one 8 oz carton RichWhip dairy-free topping mix, 3 tbsp Magnolia vanilla lemonade, and 1/2 cup powdered sugar.  Hand whisk at first, then switch to hand mixer with whisk attachment until light fluffy consistency is reached.  Use as topping for slices of the cake, or top with fresh fruit, jams, or jellies.  The cake has a wonderful shortbread-like consistency, moist but crumbly in texture, with a light lemony flavor, while the topping is more like a meringue, with stronger tones; I can best liken them to a cross between shortbread and lemon squares.  Blueberries, strawberries, raspberries, marmalade, lemon or lime curd, honey, ginger, and lingonberries are all possible toppings.

For years I bought ugli fruit for the zest alone, believing the inside to be sour and terrible.  Then I had some real fresh ugli fruit at Hy-Vee and discovered it was delicious, and perfect for cooking due to its high volume of juice production and highly aromatic zest.  Ugli fruit are the hybrid of tangerines and grapefruit, by the by; meyer lemons are the cross between mandarin oranges and lemons, smoother of skin and a bit sweeter.

This recipe is free of gluten, dairy, eggs, peanuts, nuts, and canola.

  
An Ugli Comparison
A Pair of Uglis
Ugli Fruit
Meyer Lemon Zest
Whisking 1
Whisking 2
Batter Up
A Slice of Shortbread 2a

UPDATE: Here are some variations for serving; the first features strawberries, red plum jelly, and calorie-free marshmallow topping.  The second features frozen chunks of mango mixed with squares of the shortbread cake.  For the third, I took the last bit of the original whipped topping, about a 1/4 to a 1/3 cup, and added 3 cups powdered sugar, 1/4 cup Magnolia vanilla lemonade, 1/3 cup oil, and 1 tsp gluten-free vanilla extract and whipped it together into a lovely frosting I will have to use on something else as well, as I made far too much.