Preheat oven to 350°F or gas mark 4. Grease 3 8 inch cake pans.
In a mixing bowl whisk flour, baking powder and salt until combined and set aside.
Using a stand mixer with the paddle attachment, on medium high speed, beat sugar, brown sugar, oil, eggs, and egg whites until they are all combined. Reduce the speed to low and starting with the flour mixture add ⅓ of the flour to the batter and mix until just combined. Pour in ½ of the milk, mixing until just combining. Repeat with another ⅓ of the flour and alternate with milk. Mix until just combined and be careful to not over mix scraping down the sides as necessary.
Evenly divide the batter between the three pans and gently tap to remove any large bubbles.
Bake for 20 minutes or until a toothpick/knife inserted into the center comes out clean. Remove from the oven and place the pans on a rack. They need to cool completely.
Making the frosting:
In a stand mixer with the paddle attachment, on medium high speed, beat the cream cheese until soft and fluffy. Add the sugar and vanilla and continue to mix until evenly combined. Scrape the paddle with a spatula and replace it with the whisk attachment. Add the heavy cream and beat on high speed until soft peaks form. Add the powdered sugar and whisk until firm peaks form.
Assembly
To assemble the cake start with one layer on the cake plate, top with ⅓ of the whipped cream and ⅓ of the sliced strawberries. Repeat this process with the remaining layers of cake and whipped cream. Decorate the top with the remaining strawberry slices or with whole strawberries.