Step 1: Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans or line with parchment paper.
Step 2: In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
Step 3: In a large bowl, cream together the softened unsalted butter and 1 1/4 cups of the granulated sugar until light and fluffy, about 3-5 minutes.
Step 4: Beat in the 4 eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in 1 teaspoon of the vanilla extract.
Step 5: Gradually add the dry ingredients to the wet ingredients, alternating with 1 cup of whole milk, beginning and ending with the dry ingredients. Mix until just combined.
Step 6: Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a wooden skewer inserted into the center comes out clean.
Step 7: Let the cakes cool in the pans for 10 minutes, then invert them onto a wire rack to cool completely.
Step 8: For the strawberry compote, in a medium saucepan, combine 2 cups of the chopped strawberries, 1/2 cup granulated sugar, lemon juice, and 2 tablespoons of cornstarch.
Step 9: Cook over medium heat, stirring frequently, until the mixture thickens and the strawberries soften, about 8-10 minutes.
Step 10: Remove from heat and let cool completely.
Step 11: For the vanilla custard, in a medium saucepan, whisk together the 6 egg yolks, the remaining 1/2 cup granulated sugar, and 2 tablespoons of cornstarch until smooth.
Step 12: In a separate saucepan, heat the 2 cups of whole milk and heavy cream over medium heat until it just begins to simmer around the edges. Do not boil.
Step 13: Slowly temper the hot milk mixture into the egg yolk mixture by gradually pouring a small amount of hot milk into the egg mixture while whisking constantly.
Step 14: Pour the tempered mixture back into the saucepan. Cook over medium-low heat, whisking continuously, until the custard thickens to a pudding-like consistency, about 5-7 minutes.
Step 15: Remove from heat and stir in the remaining 2 teaspoons of vanilla extract and 2 tablespoons of butter until melted and smooth.
Step 16: Pour the custard into a shallow dish, cover the surface directly with plastic wrap to prevent a skin from forming, and chill in the refrigerator for at least 2 hours, or until completely cold and set.
Step 17: To assemble, place one cooled cake layer on your serving plate. Spread half of the chilled vanilla custard evenly over the first cake layer, leaving a small border.
Step 18: Drizzle or spread half of the cooled strawberry compote over the custard layer.
Step 19: Carefully place the second cake layer on top.
Step 20: Spread the remaining custard over the second cake layer, leaving a small border.
Step 21: Top with the remaining strawberry compote, spreading it to the edges.
Step 22: Arrange the remaining 2 cups of fresh, sliced strawberries decoratively on top of the compote.
Step 23: Chill the assembled cake in the refrigerator for at least 1 hour before slicing and serving to allow the layers to set and flavors to meld.