01 - Preheat the oven to 350°F. Grease and flour an 8-inch round cake pan, ensuring even coverage to prevent sticking.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until uniformly blended. Set aside.
03 - In a large mixing bowl, beat the softened unsalted butter and granulated sugar together using an electric mixer on medium speed until the mixture becomes pale, light, and fluffy — approximately 3 to 4 minutes.
04 - Add the eggs one at a time, beating thoroughly after each addition to maintain a smooth emulsion. Stir in the vanilla extract until fully incorporated.
05 - Gently stir the finely chopped fresh basil into the wet batter, distributing the leaves evenly throughout the mixture.
06 - Alternately add the dry ingredient mixture and the combined whole milk and Greek yogurt to the batter, beginning and ending with the dry ingredients. Fold gently until just combined — avoid overmixing to keep the crumb tender.
07 - Pour the batter into the prepared cake pan and smooth the surface with a spatula. Bake for 30 to 35 minutes, or until a toothpick inserted into the center emerges clean. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
08 - While the cake cools, combine the mixed fresh berries, granulated sugar, and lemon juice in a small saucepan over medium heat. Cook for 8 to 10 minutes, stirring occasionally, until the berries soften and the mixture thickens slightly. Remove from heat and let cool completely.
09 - In a chilled mixing bowl, beat the cold heavy cream with an electric mixer until soft peaks begin to form. Add the powdered sugar and finely chopped fresh basil, then continue beating until stiff peaks hold their shape. Be careful not to overwhip.
10 - Spread the basil whipped cream evenly over the completely cooled cake. Spoon the berry compote over the cream layer just before serving. Garnish with extra fresh basil leaves or whole berries if desired.