Preheat Oven to 325 F (162 C), then grease and flour a tube pan. ( 10x4 inch, 16 Cup Angel Food Cake Tube Pan)
Using a large bowl, whisk together flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer, fitted with paddle attachment on medium speed cream together butter and sugar until fluffy. (2-3 minutes.)
Add in shortening, mix until smooth. Scrape sides and bottom of bowl as needed.
Next, add one egg at a time, mixing until incorporated.
Then, pour in milk alternating with spooning in flour mixture until a cake batter is formed. (alternating prevents curdling)
Mix in vanilla.
Spoon cake batter into prepared cake pan. Give the pan a slight bang on the counter to level batter.
Bake on middle lowest rack for 1 hr and 15 minutes. Edges of cake will be golden brown and a toothpick inserted into the cake will come out with only moist crumbs not a wet batter.
Once cake is baked, let it cool on a rack for ten minutes. Then using oven mitts invert the cake pan onto cooling rack and allow it to drop.
Let the cake cool completely before decorating with frosting and berries.