Preheat your oven to 350 degrees F (175 degrees C). Place 1 3/4 cups of sugar in a food processor and blend until superfine, about 2 minutes. This process helps to ensure that your cake will be light and fluffy.
Sift half the fine sugar, cake flour, and salt together in a bowl. This process helps to eliminate any lumps and makes the flour mixture finer, which is important for a light and fluffy cake.
Whisk egg whites, water, cream of tartar, and lemon extract together in a large bowl for 2 minutes. Beat in the remaining fine sugar using an electric mixer until medium peaks form. Sprinkle some of the flour mixture on top and stir it in gently. Repeat this process with the rest of the flour mixture. Spoon the batter carefully into an ungreased fluted tube pan.
Bake the cake in the preheated oven until it is golden brown, about 35 minutes. Invert the cake onto a cooling rack and let it cool completely, at least 25 minutes.
Beat cream cheese and 1/4 cup butter together in a bowl using an electric mixer on medium speed until it is light and creamy. Add lemon juice and beat until it is just blended. Gradually mix in all but 2 tablespoons confectioners' sugar on low speed until the frosting is just blended. Stir in lemon zest.
Mix 3/4 cup strawberries, blueberries, blackberries, and raspberries thoroughly in a bowl with 2 tablespoons white sugar.
Cut a curved, smile-shaped line near the bottom of each whole strawberry; carefully cut another, flatter curve above. Connect the two curves and carve out space between to create the smile. Leave room above the smile and below the leaves for eyeballs.
Place the reserved 2 tablespoons confectioners' sugar in a small bowl. Dust your hands with sugar and roll a tiny amount of stiff decorator icing between your fingers into a small ball. Place it on the strawberry, above the smile. Make another ball and stick it next to the first one. Stick 1 black sugar pearl onto each frosting ball to create eyes. Repeat this process with the remaining whole strawberries.
Remove the cake carefully from the pan, scraping the edges from the side if needed. Slice the cake into 6 slices about 2 inches thick. Spread 2 tablespoons of butter equally on the outside of the slices.
Heat a large skillet over medium heat. Add a cake slice and toast it until it is lightly browned, about 1 minute per side. Place the toasted cake on a plate. Spoon some frosting on top and let it drip down. Spoon sugared berries around the cake and place a smiling strawberry on top. Repeat this process with the remaining cake slices, frosting
