I like to make the soft lady finger style cookie base. I actually use Madelines, but that requires a Madeline pan...don't want to send you on a wild goose chase for one, so I recommend a basic sponge cake (mini ones will work better). Use www.foodnetwork.com to look up vanilla sponge cake recipes (should find several simple ones) You need a trifle dish (easy to find at Target or BB and Beyond) Looks like a bowl on a pedestal, typically about $10-20
Fill the bottom of the trifle dish with the sponge, the add fresh blueberries, raspberries and strawberries, then add cool whip, then add white chocolate or vanilla instant pudding (pre made and chilled), then repeat the layering process to the top, top with more berries and graham cracker crumbles (I usually use almonds, but since they are out)
This is SOOOO easy and it's fresh and pretty and elegant and it tastes wonderful and is actually a lot more healthy than a big cake or pastry. You can get fancy and soak the sponge in reduced lemongrass and raspberry, but just the basic thing is impressive enough. It will all kind of goosh together, but you want that, as long as the top looks pretty with berries and crumbles.