Preheat your oven to 350°F. In a medium bowl, whisk together the flour, baking soda, and salt. In a separate bowl, combine the melted margarine, almond milk, apple cider vinegar, vanilla extract, and lemon zest—the vinegar will react with the baking soda to help the cake rise. Pour the wet mixture into the dry ingredients and stir until just combined; don't overmix, as this keeps the cake tender.

Pour the batter into an 8x8-inch or 9-inch round cake pan. Bake for 30 minutes, or until a toothpick inserted in the center comes out clean. The cake should be golden and spring back when lightly touched. Remove from the oven and let cool for 30-45 minutes until completely cooled to room temperature.

While the cake cools, prepare your mixed berries by cutting larger ones like strawberries into roughly 1/2-inch pieces. I find that uniform berry sizes layer better in the trifle and create a more elegant presentation. Toss the prepared berries gently with the cornstarch in a bowl—this helps absorb excess moisture and prevents the trifle from becoming watery.

Once the cooled cake is at room temperature, break it into bite-sized pieces—aim for roughly 1-2 inch chunks that will look nice when layered. In a large trifle bowl or individual serving glasses, begin layering: start with a layer of cake pieces, followed by a layer of berries, then a dollop of vegan whipped topping. Repeat the layers, ending with a garnish of whipped topping and a few berries on top. I like to reserve some of the prettiest berries for the top to make the trifle look as good as it tastes!