1. Preheat oven to 335 degrees Fahrenheit.
2. Line 2 8” round cake pans with parchment paper, and spray with non-stick baking spray.
3. In a stand mixer fitted with a paddle attachment, cream butter, oil, and sugar together until smooth. Add in eggs and vanilla, then alternate dry ingredients and buttermilk until fully combined. Scrape down sides as needed.
4. Divide batter evenly among both cake pans.
5. Bake for 40-45 minutes, or until a toothpick inserted comes out clean.
6. Let cakes cool for 10 minutes at room temperature, then invert out of the cake pans and wrap with plastic wrap.
7. Chill cakes in the refrigerator for 2+ hours. To mix Chantilly cream, place cream into a stand mixer and whip until you reach stiff peaks.
8. Transfer whipped cream to another bowl and place butter, mascarpone, and powdered sugar into the bowl of the stand mixer. Add a paddle attachment and mix until smooth. Use a rubber spatula to fold in whipped cream.
9. Add in vanilla and fold until smooth. Cut strawberries into quarters and place them in a large bowl with the rest of the berries.
10. To assemble the cake, cut each cooled cake in half. Start by stacking a layer of cake. Place a dollop of raspberry jam on the cake and smooth it around the base of the cake with an offset spatula. Next, place a large dollop of Chantilly cream and spread it around with an offset spatula.
11. Top the Chantilly cream with a layer of fresh berries. Repeat the process with the remaining layers of cake, until fully assembled.
12. Chill cake until ready to serve.

Recipe Notes: Leftovers can be stored in an airtight container in the freezer for up to 3 months! To get the smoothest batter, make sure to use room temperature butter.