Step 1: Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans or line with parchment paper. Set aside.
Step 2: In a medium bowl, whisk together the sifted cake flour, baking powder, and salt. Set aside.
Step 3: In a large bowl, using an electric mixer, cream together the softened unsalted butter and 1 3/4 cups granulated sugar on medium-high speed until light and fluffy, about 3-5 minutes. Scrape down the sides of the bowl as needed.
Step 4: Beat in the eggs one at a time, ensuring each egg is fully incorporated before adding the next. Mix in 1 teaspoon of vanilla extract.
Step 5: With the mixer on low speed, gradually add the dry ingredients to the wet ingredients, alternating with the milk. Begin and end with the dry ingredients. Mix until just combined and smooth; be careful not to overmix the batter.
Step 6: Divide the batter evenly between the two prepared cake pans. Bake for 25-30 minutes, or until a wooden skewer inserted into the center of a cake comes out clean. The cakes should be lightly golden.
Step 7: Allow the cakes to cool in their pans on a wire rack for 10 minutes. Then, carefully invert the cakes onto the wire rack to cool completely before frosting. This is crucial for stability and to prevent frosting from melting.
Step 8: While the cakes cool, gently wash and pat dry your mixed berries. Hull and slice any large strawberries. In a small bowl, combine the berries with 1-2 tablespoons of granulated sugar (adjust to your sweetness preference) and 1 tablespoon of fresh lemon juice. Stir gently and set aside.
Step 9: Prepare the whipped cloud frosting: In a very cold large bowl, combine the 2 cups of cold heavy cream, 1/2 cup of sifted powdered sugar, and 1 teaspoon of vanilla extract.
Step 10: Using an electric mixer (chilled beaters are a plus!), beat the mixture on medium-high speed until stiff peaks form. Be careful not to overbeat, or the cream may become grainy.
Step 11: To assemble: Once the cake layers are completely cool, place one cake layer on your desired serving plate or cake stand.
Step 12: Spread about half of the whipped cloud frosting evenly over the top of the first cake layer, leaving a small border around the edge.
Step 13: Arrange half of the sugared mixed berries evenly over the frosting layer.
Step 14: Carefully place the second cake layer on top of the berries and frosting.
Step 15: Spread the remaining whipped cloud frosting over the top and sides of the entire cake, creating a smooth or rustic finish as desired.
Step 16: Decorate the top of the cake with the remaining fresh mixed berries. You can arrange them in a beautiful pattern or pile them loosely for a natural look.
Step 17: For best results, refrigerate the Berry Cloud Layer Cake for at least 30 minutes before slicing and serving. This allows the frosting to set and the flavors to meld beautifully. Store any leftovers in an airtight container in the refrigerator.