Lemon Angel Food slices

I've bookmarked a few Angel Food recipes found on Pinterest, those which promise a light fluffy sponge by mixing a cake mix with just one or two extra ingredients.
As it's impossible to find Angel Food cake mix in the British supermarkets, you can buy them online or find in a deli. I bought a box of six from the devil incarnate also known as amazon. I used Duncan Hines brand, but I suppose any other brand of Angel Food cake mix would do. The cake mix doesn't require anything but water.
The original pin which I used as my reference brought me to the post - see Two Ingredients Lemon Bars - it asked for a tin of lemon pudding filling, another American product which is not easily available in the UK.
Thankfully, Waitrose sells a powdered Green's Lemon Pie Filling. It comes in a small box containing two sachets, and requires an egg yolk and water.

Lemon Angel Food slices (makes 28+ slices)
Ingredients:
Angel Food cake mix (453g), for example, Duncan Hines
1 sachet of Green's Lemon Pie filling
2 lemons, zest and juice
water
icing sugar (about 8 heaped tbsp)

First mix the contents of one sachet of lemon pie filling with the water (280ml) and 1 egg yolk, beat them together, and stir over a pan of boiling water for about 3-4 minutes. It only needs to get creamier rather than cooked to a thick consistency, as when you cook it as a separate dessert. Let it cool a bit.
In a big bowl mix the Angel Food cake mix with lemon pie filling. Add the juice and zest of 1 lemon. It immediately fluffs up and grows in size considerably.
I used two brownie trays (medium-sized) for baking the angel slices. Plus I had enough for six cupcakes. Bake the slices/cupcakes at 180C for about 25 minutes.

Remove the trays from the oven, let them cool before turning out onto a flat surface.
Mix the icing sugar with the juice of one lemon and cover the big cakes with it. Then slice into smaller size portions, a bit like Mr Kipling's angel or lemon slices.

Traybake before being iced and sliced + sliced pieces

The resulting slices were delicious, very light, airy, fluffy and moreish. You wouldn't believe that they were made, using two packs of mixes. I will definitely be baking them again. Next time I will try to use an orange zest and juice, or a mix of lemon and orange.