First decide if you are going to bake the batter into cake pans or a sheet pan like I showed in the video tutorial
Preheat the oven to 350°F then grease & parchment line your cake pan(s)
Prepare the recipe for yellow cake as per the instructions on that page & bake in your specified cake pan(s)
Meanwhile make the simple syrup by combining the water & sugar together in a small sauce pot, bring to a rolling boil
Reduce heat, add the 5 large chopped strawberries & simmer for 3 minutes
Cool slightly then carefully pour the hot syrup with the berries into a blender & puree smooth, reserve until later
Separate the 12 large~ same sized ~same height strawberries & cut the stems off each one. Then cut each one in half, reserve until later
Chop enough strawberries for the filling to total 1½ cups reserve for later
Once the cake is baked & fully cooled, trim if necessary & then line a 9" cake ring or a spring form pan *with the bottom removed* with an acetate cake strip
Place one of the cold cake layers in the bottom & brush generously with strawberry simple syrup
Arrange the halved strawberries around the entire edge of the cake ring with the sliced side facing out
Next prepare the vegan whipped cream of your choice (you will need 2 cups fully whipped cream) Reserve in the refrigerator until needed
Prepare the pastry cream custard by combining the sugar with the cornstarch & agar powder then add that to the plant milk in a large sauce pot
Bring everything to a full rolling boil over medium to high heat whisking constantly to avoid scorching
Once it comes to a full boil remove from the heat add the vegan butter & whisk smooth
Transfer the hot custard to a large mixing bowl & whisk to release the intense heat.
Continue whisking every so often until the custard is slightly cooler than body temperature, once it is cool add the vegan whipped cream in 2 additions, whisking & folding gently to incorporate
Pour half of the diplomat cream over the sponge cake in the ring mold be sure to cover the tops of the strawberries
Sprinkle the chopped strawberries over top of the cream then add the other layer of sponge cake that has been brushed with more strawberry syrup
Gently press down to make a tight seal & refrigerate the entire cake for at least 4 hours or preferably overnight
Remove the ring mold then carefully remove the acetate strip
Powdered sugar on top, sliced strawberries & almonds are optional garnish!