Part cheesecake and part cookie, this dessert defies definition. The secret to this recipe is in the cake mix, which cuts way back on all the prep time to ensure you can have homemade cookies in under an hour flat.
Preheat the oven to 375 degrees F. Lightly coat a 9 x 13-inch baking dish with cooking spray.
In a stand mixer fitted with the paddle attachment, combine the cake mix, melted butter, and 1 of the eggs. Mix on medium-high speed for 2 minutes, until all the ingredients are well combined; the batter will be very stiff.
Use your hands to press the batter in an even layer on the bottom and 1/2 inch up the sides of the prepared baking dish. Spread the strawberry jam over the batter in an even layer.
In the same stand mixer bowl, combine the cream cheese, the remaining 2 eggs, and the vanilla and mix on medium until completely smooth, about 3 minutes. Pour the cream cheese mixture into the baking dish, keeping it inside the raised edges of the bottom layer. Bake for 30 to 35 minutes, until the top is just beginning to brown and the cheesecake layer is almost firm in the center.
Cool completely on a wire rack. If not serving immediately, cover loosely with plastic wrap and refrigerate. Cut into bars or small squares to serve, garnishing each with a slice of fresh strawberry, if desired.
