Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, or line bottoms with parchment paper.

Melt the unsalted butter and set aside to cool slightly.

In a large heatproof bowl (preferably the bowl of your stand mixer), combine the large eggs and 1 cup granulated sugar. Set the bowl over a saucepan of simmering water (do not let the bowl touch the water). Whisk constantly until the mixture is warm to the touch (about 110°F / 43°C) and the sugar has dissolved.

Remove the bowl from heat. Using a stand mixer with the whisk attachment (or a hand mixer), beat the egg-sugar mixture on high speed for 7-10 minutes, until it's very thick, pale yellow, and has tripled in volume. When you lift the whisk, the batter should fall in a thick ribbon that holds its shape for a few seconds.

Sift together the all-purpose flour, baking powder, and salt. Gradually fold the dry ingredients into the egg mixture in 3 additions, using a rubber spatula. Be gentle to maintain the volume.

Take about 1/2 cup of the batter and whisk it into the cooled melted butter and vanilla extract. This tempers the butter. Then, gently fold this butter mixture back into the main batter until just combined, being careful not to deflate it.

Divide the batter evenly between the two prepared cake pans. Smooth the tops.

Bake for 25-30 minutes, or until a wooden skewer inserted into the center comes out clean and the cakes spring back when lightly touched.

Let the cakes cool in the pans for 10 minutes, then invert them onto a wire rack to cool completely.

While the cakes cool, gently wash, hull, and slice the fresh strawberries.

In a medium bowl, combine the sliced strawberries with 1/4 cup granulated sugar and optional lemon juice. Stir gently and let them macerate for at least 15-20 minutes, or until they release some juice.

Ensure your mixing bowl and whisk attachment (or beaters for a hand mixer) are very cold (chill them in the freezer for 10-15 minutes prior).

Pour the very cold heavy cream into the chilled bowl. Add the sifted powdered sugar and vanilla extract.

Beat on medium-high speed until stiff peaks form. Be careful not to overbeat, or it will turn to butter.

Once the sponge cake layers are completely cool, use a serrated knife to level the tops if necessary, creating flat surfaces.

Place one cake layer on your serving platter or cake stand. You can brush it lightly with some of the collected strawberry juice if desired for extra moisture and flavor.

Spread about 1/3 of the whipped cream evenly over the first cake layer.

Arrange about half of the macerated strawberries (draining off excess juice if too much) over the whipped cream.

Carefully place the second cake layer on top. Repeat with another 1/3 of the whipped cream and the remaining strawberries.

Top with the remaining whipped cream, spreading it evenly over the top and sides of the cake.

Garnish with a few whole or fanned strawberries, if desired.

Chill the cake in the refrigerator for at least 1-2 hours before slicing and serving. This allows the flavors to meld and the cream to set.