Prepare the sponge cake base first. Line a 9 or 10-inch spring form pan with parchment paper. Preheat oven to 350F.
Place the eggs and sugar into mixer bowl and whisk on high speed for 7 to 8 minutes until eggs are very voluminous and almost white in color. In a separate bowl, combine the flour and baking powder. Sift small amounts of flour into the eggs and fold gently but thoroughly after each addition. Fold in the diced strawberries and vanilla extract at the end. Pour the cake batter into the prepared spring form pan and bake in preheated oven for 18 to 20 minutes or until the top is golden brown. Remove the cake and allow it cool.
Meanwhile, prepare the mousse. Place the strawberries, strawberry extract and sweetened condensed milk into a food processor and pulse into a puree; set aside. Pour the heavy cream into a mixer bowl and add the sugar. Whisk until a light and fluffy whipped cream forms. Add the softened whipped cream cheese and whisk until smooth. Fold in the strawberry puree and add the diced strawberries.
Combine the water and gelatin in a small saucepan or microwave safe cup. Heat or microwave the gelatin until it's completely dissolved. Add the dissolved gelatin into the mousse and fold until combined. Pour the prepared mousse over the cooled sponge cake.
For the garnish, slice about 15 strawberries and arrange them overlapping each other, starting from the outside edge and working in. Refrigerate the cake for about 1 hour.
Prepare the strawberry jello with half of the water required per instructions. This will ensure the jello layer is firm. Pour the jello over the top of the sliced strawberries. Place cake bake into the refrigerator until set completely. To remove cake from pan, run a flat spatula along the edge, then release pan.