Preheat oven to 375 degrees. Lightly grease a 9x13-inch baking pan with cooking spray.

In a large mixing bowl, beat the shortening and sugar till very light, about 2-3 minutes. Beat in eggs one at a time, and then add vanilla.

In a separate bowl, combine the flour, baking powder and salt. Add the dry ingredients alternately with milk, mixing in about ½ the dry ingredients, then adding half the milk and mixing well to incorporate, then repeating with the remaining flour mixture and milk.

Spread the batter into the prepared baking pan and bake for 30-35 minutes, making sure to check the cake with a toothpick for doneness. Be careful not to overbake the cake.

In a large bowl, combine mashed strawberries with sugar, to taste. If your berries are really sweet, then not much more than a tablespoon or two of sugar may be necessary. Set aside to allow the sugar to draw out the juices of the berries.

In a separate bowl, whip the cream on medium speed until soft peaks begin to form, about 2-4 minutes. Add the powdered sugar and vanilla and whip on medium speed another 2 minutes, until soft peaks return. Be sure not to overwhip the cream - it should just be soft and holding it's shape without being firm or thick.

Top each slice of cake with a generous spoonful or two of berries and a nice dollop of whipped cream.