Valentine's Day Cake

Name: Valentine's Day Cake
Cook time: 2 h
Total time: 2 h
Cuisine: American
Ingredients: 1/2 cup bittersweet chocolate chips (3 oz.); 1/3 cup boiling water; 3/4 cup (6 oz.) salted butter, softened, plus more for greasing pans; 1 1/2 cups granulated sugar; 3 large eggs, separated; 1 teaspoon vanilla extract; 1 1/2 cups (about 6 3/8 oz.) all-purpose flour, plus more for pans; 3 tablespoons unsweetened cocoa; 3/4 teaspoon baking soda; 3/4 teaspoon table salt; 3/4 cup whole buttermilk; 3/4 cup (6 oz.) salted butter, softened; 4 1/2 cups (about 18 oz.) powdered sugar; 1/4 teaspoon table salt; 1/3 cup finely chopped fresh strawberries (from about 3 large strawberries); 1 to 2 drops soft pink food coloring gel; Pink sanding sugar (optional); Sliced strawberries