• Preheat oven to 350℉. Butter and flour an 18-by-13-inch rimmed baking sheet or sheet cake pan. In a mixing bowl whisk together flour, cornstarch, salt, baking soda and baking powder, set aside.
• In the bowl of an electric stand mixer fitted with the paddle attachment whip together butter, sugar and lemon zest until pale and fluffy. Mix in eggs one at a time then mix in vanilla. If you are using beaters and a bowl whip until pale and fluffy.
• Add 1/3 of the flour mixture and mix just until combined then add in 1/2 the sour cream and mix just until combined, repeat with flour and sour cream once more then end by mixing in the last 1/3 of the flour mixture and mixing just until combined (scrape down bowl to make sure it's evenly combined). 
• Pour and spread batter evenly into prepared baking sheet. Bake in preheated oven until toothpick inserted into center comes out clean, about 20 - 24 minutes. 
• Remove from oven and cool completely on a wire rack. Once cool cut into 24 rounds the size of your dessert cups (you'll have a little left over cake which you can chill or freeze and serve later with more fresh fruit and whipped cream).
  

For Strawberry Layer

• Toss diced strawberries with sugar. Let rest 10 minutes.
  

For Strawberry Whipped Cream Cheese Layer

• In a large mixing bowl using an electric hand mixer whip heavy cream until soft peaks form (no need to clean beater blades for next step).
• In a separate medium mixing bowl whip cream cheese until smooth, add powdered sugar and vanilla and whip until light and fluffy. Add cream cheese mixture to heavy cream and whip until stiff peaks form.
• At the end add 1/2 cup of strawberries from the diced strawberry mixture and some of the strawberry juice mix well with the mixer or beater till the strawberries a thuroughly encorperated and set aside.

Assemble the Cake In The Cup

• With the top of the jar cut a circle in the cake.
• Pipe into the bottom of the jar a layer of cream then add about a Tbsp of the strawberry mixture then add another layer of cream. Then take the circle of cake that you cute using the mason jar and layer that on top of the cream and repeat the process until the jar is full. Finish off with garnishing of a whole strawberry and a sprinkle of the lemon zest.
• You can add a cute twine and wooden spoon to finish the affect. It's a great treat for any celebration!