Preheat your oven to 350°F (175°C) and prepare two 8-inch round cake pans by spraying them with nonstick spray. Line the bottoms of the pans with parchment paper for easy removal. In a medium bowl, whisk together the cake flour, baking powder, baking soda, and salt until well combined. In a large mixing bowl, beat the butter and sugar on medium speed until the mixture becomes light and fluffy. Add the vanilla extract and continue beating. Incorporate the eggs one at a time, beating well after each addition. In a separate small bowl, combine the buttermilk and Greek yogurt. Lower the mixer speed to low and gradually add the dry ingredients in three parts, alternating with the buttermilk mixture—starting and ending with the flour mixture. Mix just until combined to avoid overmixing. Divide the batter evenly between the prepared cake pans and smooth the tops with an offset spatula. Tap the pans firmly on the counter to release any trapped air bubbles. Bake the cakes for 24 to 25 minutes, or until the tops and edges turn golden, the cakes spring back when lightly touched, and a toothpick inserted into the center comes out clean or with a few moist crumbs. Let the cakes cool in their pans on a wire rack for 15 minutes before carefully inverting them onto the racks to cool completely.

For the strawberry frosting, combine the sliced strawberries and sugar in a saucepan. Heat over medium-high heat, stirring constantly and pressing the berries with a spatula to release their juices. Once it reaches a boil, reduce the heat to low and simmer for 8 to 9 minutes, stirring frequently, until the mixture has reduced and thickened into a purée. Transfer the purée to a bowl and refrigerate for at least 1 hour to chill. In a large mixing bowl, beat the butter and salt on medium speed until light and fluffy. Add the vanilla extract. Gradually add the powdered sugar one cup at a time on low speed, scraping down the sides of the bowl as needed. Slowly incorporate 4 tablespoons of the chilled strawberry purée until combined. Increase the mixer speed to medium-high and beat the frosting for 1 minute to make it light and airy.

To assemble the cake, place one cake layer on a rotating cake stand. Use an offset spatula to spread a swirl of frosting evenly across the surface. Pipe a ring of frosting around the outer edge of this layer to create a border, then chill it in the refrigerator for 10 minutes. Fill the center of the frosted layer with 1 cup of thinly sliced fresh strawberries. Spread a thin layer of frosting on the second cake layer and carefully place it frosting-side down over the strawberries. Chill the stacked cake for 20 minutes to set.

Next, use the offset spatula to cover the top and sides of the cake with a smooth layer of frosting while rotating the cake stand. Use a bench scraper to gently smooth the edges and remove any excess frosting. If desired, pipe any remaining frosting decoratively on the top of the cake. Chill the frosted cake for 30 minutes before serving, and garnish with fresh strawberries. Store any leftovers covered in the refrigerator for up to 2 days, and be sure to bring the cake back to room temperature before serving for the best texture and flavor.