First of all, Place strawberries in a blender or food processor. Puree until smooth. Place the mixture in a saucepan. Bring to a boil. Now Let the mixture simmer for 20 minutes, stirring occasionally. The reduced strawberry puree should yield just under 1 cup. You can save the rest for the frosting and cake batter.
Lightly grease two 9-inch baking pans. Place parchment paper on the bottom. Preheat the oven to 350°F.
In a large bowl, beat butter, vegetable oil, and sugar until smooth. This should take about 2 minutes. Add 1 cup strawberry puree, sour milk, vanilla, and strawberry extracts to the batter. You can use any strawberry puree leftover (up to 1/4 cup) for the frosting.
Combine the buttermilk and eggs in a bowl. Set aside. Mix the cake flour, baking powder, salt, and in a separate bowl. 6 Add 1/3 of the dry ingredients into the butter mixture. Mix until well combined. Mix in half the milk mixture. Continue to add 1/3 of the dry ingredients, until well combined.
After this, add the rest of the milk mixture. Mix the remaining dry ingredients into the mixer. Now Use a rubber spatula or a hand mixer to combine the mixture. Scrape the bottom and sides of the bowl to ensure everything is well combined.
Now Divide the batter equally between the prepared pans. Bake at 350 degrees for 25-30 minutes.
Strawberry Chantilly cream: Use a hand mixer in a large bowl to whip cream and vanilla extract. While mixing, slowly add strawberry jello.
Slowly add 1/2 cup powdered sugar to the cream until it reaches soft peaks. Continue beating until stiff peaks form.
Combine cream cheese, mascarpone, and 1/4 cup strawberry puree in a separate bowl. Beat until smooth and whipped, approximately 2 minutes. Mix in 1 1/2 cups powdered sugar.
After this, Use a rubber spatula or a whisk to fold the cream cheese mixture into the whipped cream mixture.