Preheat the oven to 350° F. Butter and flour two 8" square pans or two 9" round cake pans. Add in a parchment paper sling and butter it.
In a medium sized bowl, whisk together flour, cocoa, salt and baking soda. Set aside.
In the bowl of a stand mixer, cream together butter and sugar until light and fluffy.
Mix in eggs one at a time. Add in buttermilk, vanilla extract and red food gel. Mix until combined.
Pour into two pans. Bake for 30-35 minutes, until a toothpick inserted into the center comes out with just a few crumbs.
While cake is cooling, whisk together both boxes of instant pudding with 4 cups of cold milk. Place in the refrigerator for at least 5 minutes.
Once cake is cool, cut out your star shapes (using directions below) and cut the rest of the cake into cubes.
Begin layering ingredients in a trifle bowl, regular bowl, or in cups. Start with adding in half of the cake cubes, then gently add on half of the pudding, half of the cut strawberries, and half of the blueberries.
On top of the blueberry layer, add in the rest of the pudding, the rest of the cake, and the rest of the berries (I combined the strawberries and blueberries on top). Add dollops of thawed whipped topping and add your cake stars on top of whipped topping.