Preheat your oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper to prevent sticking and ensure even baking.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set this aside—you’ll need it in just a moment.

In a large mixing bowl, beat the softened butter, vegetable oil, and granulated sugar until the mixture becomes light and fluffy, about 3 to 4 minutes. It should look pale and airy.

Crack in the eggs one at a time, beating well after each addition. Mix in the vanilla extract until the batter is smooth and well blended.

Add the dry ingredients in three parts, alternating with the buttermilk in two parts. Begin and end with the dry mix. Stir just until combined—do not overmix or the cake could turn out dense.

Toss the diced strawberries with a tablespoon of flour (this helps them suspend in the batter). Gently fold them into the batter using a spatula to avoid crushing them.

Divide the batter evenly between your prepared pans. Bake for 25–30 minutes or until a toothpick inserted in the center comes out clean. The tops should be lightly golden and springy to the touch. Let them cool in the pans for 10 minutes before transferring to wire racks to cool completely.

In a large chilled bowl, whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form. Be careful not to overwhip—it should hold its shape but still look smooth and silky.

Place one cake layer on your serving plate. Spread a generous layer of whipped cream on top and sprinkle with extra diced strawberries if you like. Add the second cake layer on top and frost the top and sides with the remaining whipped cream.

Garnish with whole strawberries on top for a beautiful finish. Chill the cake for at least 30 minutes before slicing—this helps the layers set and makes it easier to serve.