1. Preheat the oven to 350°F and grease a 9×13-inch baking pan.

2. In a medium bowl, whisk together the flour, baking powder, and salt.

3. In a large bowl, beat the butter and granulated sugar until light and fluffy.

4. Add the eggs one at a time, mixing well after each addition, then mix in the vanilla extract.

5. Add the dry ingredients in batches, alternating with the milk, and mix just until combined.

6. Spread the batter evenly into the prepared pan.

7. Bake for 28 to 34 minutes, or until a toothpick inserted in the center comes out clean.

8. Let the cake cool completely in the pan.

9. In a bowl, toss the sliced strawberries with the strawberry jam and let them sit for 10 to 15 minutes.

10. In another bowl, beat the cream cheese and powdered sugar until smooth.

11. In a separate bowl, whip the heavy cream until soft peaks form, then fold it into the cream cheese mixture.

12. Spread the whipped topping over the cooled cake.

13. Spoon the strawberry mixture over the top just before serving.

14. Chill for 20 to 30 minutes if you want cleaner slices.