Allergy free shortbread

Gluten and dairy free recipe I made for my young friend who has deadly allergies. Before cooking anything I double clean my kitchen and pans, utensils, etc. Even if they are already clean I clean them again. Wipe the counter with bleach solution. Any cutting boards must be plastic and thoroughly cleaned. No cast iron, only stainless steel or similar cleanable equipment (copper, etc). Start with a basic shortbread recipe. 2 cups flour. Use Bobs Red Mill Gluten Free Flour 1 cup butter. Use crisco 100 percent vegetable shortening. Just in case you used a wheat flour contaminated spoon or anything, use a brand new container. 1/2 cup Powdered sugar just be sure to read the label make sure it’s 100 percent. Some companies use flour to bulk it up. Before you start baking, take a super clean (my friend’s allergies could kill him) stainless steel pan (I usually cook in cast iron) and heat 1 cup of water, 1/2 cup of sugar. Dissolve the sugar. Next, add 8-16 oz fruit such as blueberries, raspberries, anything fresh. Cook on low heat for a while, stirring regularly until it thickens. See photo. The sauce is thickening as a spoon dragged across it leaves tracks. Shut off heat. Make the shortbread. Place in pan, forming into a bottom layer and pressing down. Pay extra attention to the edges. Bake at 350 for 10-15 minutes. Remove from oven and quickly spread the fruit topping over the shortbread. Return to the oven for another 10-15 minutes. Cool about 10 minutes then slice. Keep in freezer if not to be consumed immediately. I wrap each slice in waxed paper then freeze, once frozen I put in ziplock bags. The whole thing is to be sure not to cross contaminate my friend with allergens.