Creating the Mixed Berry Chantilly Cake requires just a few straightforward steps. Follow this guide to ensure success:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Mix Dry Ingredients: In a large bowl, sift together the all-purpose flour, baking powder, and salt.
3. Cream Butter and Sugar: In another bowl, beat the softened butter and granulated sugar until the mixture is light and fluffy.
4. Incorporate Eggs: Add the eggs one at a time to the butter-sugar mixture, beating well after each addition.
5. Add Milk and Vanilla: Gradually mix in the whole milk and vanilla extract until fully combined and smooth.
6. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, stirring until the batter is smooth and free of lumps.
7. Bake the Cake: Divide the batter evenly between the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool the Cakes: Allow the cakes to cool in the pans for about 10 minutes before transferring them to wire racks to cool completely.
9. Prepare the Chantilly Cream: While the cakes cool, whip the heavy cream and powdered sugar in a bowl until soft peaks form.
10. Assemble the Cake: Once cooled, place one cake layer on a serving platter. Spread a generous layer of Chantilly cream over it, followed by the mixed berries.
11. Layer the Second Cake: Place the second layer of cake on top and repeat the process of adding Chantilly cream and berries.
12. Final Touch: Garnish the top with additional berries and a dusting of powdered sugar, if desired.

These steps will guide you in effortlessly creating this beautiful and delicious cake.