Preheat your oven to 350°F. In a medium bowl, whisk together the flour, baking powder, and salt until fully combined, then set aside. Using a stand mixer fitted with the paddle attachment (preferred) or a hand mixer, beat the sugar, oil, eggs, egg whites, and extracts until well combined. Add the sour cream and continue beating until incorporated. Gradually add half of the flour mixture and beat just until combined. While mixing, slowly pour in the milk, followed by the remaining flour mixture. Be sure to scrape down the sides and bottom of the bowl as needed. Take care not to overmix the batter. Line three 8-inch cake pans with parchment paper and grease them. Evenly divide the batter among the pans, then gently tap the pans on the countertop a few times to release any air bubbles. Bake for 18–22 minutes, or until a toothpick inserted into the center comes out clean. Rotate the pans halfway through baking if necessary to ensure even browning. Remove from the oven and place the pans on a rack to cool completely.

Combine the sliced or diced strawberries with the strawberry jam and set aside. These will be used for both the filling and the topping. Note: For the filling, use about 2½ cups of sliced strawberries, and for the top of the cake, dice about ½ cup of strawberries. You’ll need approximately 3 cups total.

In a large mixing bowl, place the cream cheese, powdered sugar, and vanilla extract. Using a stand mixer with a whisk attachment (preferred) or a hand mixer, beat on medium speed until smooth. While the mixer is running, slowly pour the cold heavy cream down the side of the bowl. Pause occasionally to scrape the sides and bottom of the bowl. Increase the speed to high and whip until stiff peaks form. It’s crucial to keep the cream cold throughout the process to ensure it thickens properly. If using a hand mixer, hold the bowl near the top and avoid pressing it against your body to keep it cool.

Place one cake layer on a serving platter. Spread one-third of the whipped cream frosting evenly over the layer, then top with about 1¼ cups of the prepared strawberries. Add the second cake layer and repeat the process. For the final (top) layer, cover with the remaining frosting and arrange the remaining strawberries in the center. Optionally, decorate the outside of the cake with whole strawberries for a beautiful finishing touch.