Crumbly crust- Preheat oven to 375 degrees F. Lightly grease a 9 by 13- inch baking pan and set aside. In a large mixing bowl add the flour, sugar, baking powder and mix until blended. Add the pieces of butter to the mixture, with a pastry cutter or by hand work in the butter (I prefer doing this by hand).
You will want to end up with a mixture of crumbs the size of peas. Take a little more than half of the crumbs and press into the prepared baking pan. Place in the preheated oven for 10 to 12 minutes or until lightly browned. Place the remaining crumbs in the refrigerator to keep cold
Cream cheese filling- While the bottom crust is baking add the cream cheese to a medium bowl and beat with an electric mixer until fluffy. Add the sugar, sour cream, egg, and vanilla and mix until smooth.
Strawberries filling - While the bars are baking in a medium bowl toss the sliced strawberries with the sugar and cornstarch.
Assembling - Once the bottom crust is baked remove from the oven. Spread the cream cheese mixture evenly over the top of the crust. Take the strawberries and sprinkle evenly over the top of the filling.
Take the rest of the crust mixture and crumble evenly over the berries. Place bake in the oven and bake 35 to 40 minutes until lightly browned. Remove from oven and cool before cutting into bars.