Divide the batter between the 2 pans, tap the pans firmly on the counter to ensure that no air bubbles are trapped in the batter and that the batter is level.
Bake on the middle rack of the preheated oven for 60-75 minutes until the cakes are golden brown and a toothpick inserted into the center comes out clean.
Allow the cakes to cool completely on wire racks in the baking pans.
Make the icing:
Place the softened vegan butter in a mixing bowl and beat until light and fluffy. Add the vanilla and mix once more until combined.
Add the powdered sugar 1/2 cup at a time and continue mixing until thick and creamy. Drizzle in the non-dairy milk a little at a time to thin. Gently fold in the berries.
If icing and decorating the cake:
Once the cake layers have cooled wrap them individually in plastic wrap then place in the freezer until frozen solid about 4-6 hours.
Once frozen, remove and unwrap the first layer and carefully use a serrated knife to level the top of the cake. This will ensure the layers are beautiful once you cut a slice. Repeat the process with the second layer.
Place the first layer, leveled side up, on a cake stand and add about 1/2 cup of the prepared strawberry buttercream icing on top, smooth out evenly towards the edges with an offset spatula then gently place the second layer, leveled side up on top.
Starting with the sides ice the cake using the offset spatula to create a smooth finish to the icing. Once the cake is completely iced transfer to the refrigerator to chill.
Place a sheet of parchment paper across the top of your iced cake, directly down the center. Drizzle melted chocolate, from dipping the strawberries, across the top of the cake and down the sides. Since the cake is chilled the chocolate will almost instantly harden. Once you are happy with the chocolate drizzle and it has set, remove the parchment and decorate the other half of the cake with the vegan salted chocolate covered strawberries and the plain berries. Serve immediately and store any leftovers covered in the refrigerator for up to 3 days.