Preheat oven to 350º.
Grease and flour 2 9″ round cake pans.
In a large bowl, cream together the butter, sugar and dry gelatin until light and fluffy, about 2 minutes. Add egg yolks, one at a time, mixing well after each. Combine flour and baking powder; stir into batter alternately with milk. Stir in vanilla and strawberry puree.
Whip egg whites with remaining 2 tablespoons sugar until soft peaks form. Gently fold into cake batter and then spread batter into prepared pans.
Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Allow cakes to cool in pans for about 5-10 minutes before turning out to cool completely.
Place cold cream, sugar and vanilla in a stand mixer bowl and whip until soft peaks form.
When cake is cool, gently break into chunks with your hands. Layer into mason jars using whipped cream, jam, fresh berries and cake pieces. You can screw on a lid and store these overnight in your fridge–they are great the next day or travel well to picnics!