In a medium bowl, toss the sliced strawberries with the granulated sugar and lemon zest. Let them sit at room temperature for at least 30 minutes so they release their juices.

Preheat the oven to 350°F. Grease a 9×13-inch sheet pan or baking pan.

In a large bowl, cream the softened butter and sugar until light and fluffy. Add the eggs one at a time, then mix in the vanilla extract.

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

Gradually add the dry ingredients and milk to the butter mixture, alternating between the two and mixing until just combined.

Spread the batter evenly into the prepared pan. Bake for 22 to 25 minutes, or until a toothpick inserted in the center comes out clean.

Let the cake cool completely before adding the topping.

To make the whipped cream, beat the cold heavy cream, powdered sugar, and vanilla until stiff peaks form.

Spread the whipped cream evenly over the cooled cake.

Spoon the macerated strawberries and their juices over the whipped cream just before serving. Slice and serve.