1-Preheat oven: Preheat oven to 325°F (163°C). Line two 8-9 inch round baking pans with parchment paper and spray with nonstick cooking spray.

2-Whisk mixture: Whisk together flour, baking powder, baking soda, and salt in a large bowl.

3-Mix liquids: Mix milk and vanilla extract in a liquid measuring cup; set aside.

4-Cream ingredients: Using a mixer, cream together butter, vegetable oil, and sugar until combined.

5-Add eggs: Add eggs and egg whites one at a time, mixing until light and fluffy.

6-Combine mixtures: Alternate adding the flour mixture and milk mixture into the butter mixture, starting and ending with the dry ingredients. Mix until smooth but do not overmix.

7-Prepare pan: Divide batter evenly between the pans; smooth the tops.

8-Bake cake: Bake for 30-40 minutes on the lower two-thirds of the oven. Test doneness with a toothpick.

9-Cool layers: Cool in pans for 15-20 minutes, then transfer to racks to cool completely.

10-Whip cream: Whip heavy cream, vanilla extract, and powdered sugar until stiff peaks form.

11-Prepare filling and frosting: Reserve half the whipped cream plain for frosting. Mix diced strawberries into the other half for the filling.

12-Slice layers: Cut each cake layer horizontally in half, making four thinner layers.

13-Layer cake: Layer the cake by spreading one-third of the strawberry whipped cream filling between each layer.

14-Frost and decorate: Frost the entire cake with the plain whipped cream. Decorate the top with sliced strawberries.

15-Chill cake: Refrigerate cake for at least 4 hours or overnight to set before serving.