To make the cake, first, preheat the oven to 350°F and grease the bottom and sides of a 9 x 13 inch baking pan.
Stir or whisk ⅔ cup of the milk together with the ground flaxseeds. Let the mixture sit for at least five minutes to gel.
While the flax mixture sits, whisk the flour, baking powder, baking soda, and salt together in a large mixing bowl.
Once the flax mixture has sat for a few minutes, add the sugar, butter, vanilla, and cider vinegar to the bowl. Use an electric mixer to beat the mixture at high-speed until combined and slightly frothy, about one minute.
Begin alternating adding the flour mixture and the remaining ⅔ cup of milk to the bowl with the flax mixture, adding about a third of each at a time and beating each addition in at low speed.
Pour the batter into the prepared baking pan.
Bake the cake for 24 to 26 minutes, until a toothpick inserted into the center comes out clean.
Place the cake on a cooling rack and let it cool completely.
Once the cake has cooled, stir the milk mixture ingredients together in a medium bowl or container.
Use a fork to gently poke holes about a half inch apart all over the cake, then pour the milk mixture over the cake.
Cover the cake and chill it for at least one hour.
To make the whipped topping, first open the cans of coconut cream. They should have separated into a solid portion and a watery liquid. Pour off the liquid, then transfer the solids to a large mixing bowl.
Use an electric mixer at high-speed to beat the coconut cream until fluffy, about one minute. Add the powdered sugar and vanilla and continue beating the ingredients until combined.
Spread the whipped coconut cream over the cake. Optionally, top it with a sprinkle of cinnamon and some fresh strawberries. Slice and serve the cake immediately or chill until ready to serve (Note 1).