1. Prepare the Signature Burnt Sugar Syrup (Best Made Ahead!): In a sturdy, medium saucepan, gently melt 1 cup of granulated sugar over medium heat, stirring constantly with a wooden spoon. It will transform into a beautiful amber brown caramel in about 8-10 minutes. Turn the heat to low, then very carefully and slowly drizzle in the boiling water – it will sizzle a lot! Stir after each addition. Once all the water is in, cook for just 3 more minutes on low. Remove from heat and let it cool completely, ideally overnight, until thick and ready to use. This yields about 1 cup.
2. Preheat & Prep Pans: Get your oven ready by preheating to 350°F (177°C). Lightly grease two 9-inch cake pans, line the bottoms with parchment paper circles, and grease the parchment too. This makes sure your cakes release perfectly!
3. Whisk Dry Ingredients: In a medium bowl, simply whisk together the cake flour, baking powder, baking soda, and salt. Set this aside.
4. Cream Butter & Sugar: In a large mixing bowl (using a hand or stand mixer), beat the softened butter and granulated sugar together on high speed until they're light, fluffy, and perfectly creamed, which takes about 2 minutes.
5. Mix in Wet Goodness: With the mixer on medium speed, pour in half (1/2 cup) of your cooled burnt sugar syrup and beat until fully blended. Next, beat in the egg whites, sour cream (or yogurt), and vanilla extract until well combined.
6. Combine Wet & Dry Gently: Reduce your mixer speed to low. Gradually add the dry ingredient mixture to the wet, mixing just until combined. With the mixer still on low, slowly pour in the milk until everything comes together. Remember, don't over-mix for a super tender cake! The batter will be slightly thick.
7. Bake to Golden Perfection: Divide the cake batter evenly between your two prepared pans. Bake for 23-25 minutes, or until a toothpick inserted into the center of a cake comes out clean. The syrup gives the cakes a lovely golden crust! Let them cool completely in their pans on a wire rack.
8. Whip Up the Creamy Frosting: While the cakes cool, let's make the frosting! In a large bowl (with your mixer and paddle attachment), beat the softened butter on medium speed until creamy, about 1-2 minutes. Add the confectioners' sugar, the remaining 1/2 cup of cooled burnt sugar syrup, vanilla extract, milk/cream, and salt. Beat on low speed for 30 seconds, then crank it up to high and beat for about 2 minutes until it's wonderfully smooth and light. Taste and adjust salt if you love that salty-sweet kick!
9. Assemble Your Dream Cake: Once your cakes are fully cool, use a large serrated knife to level the tops for a flat, beautiful surface. Place one cake layer on your serving plate. Spread an even layer of frosting over it, then drizzle about 1/4 cup of your cooled salted caramel on top of the frosting. Gently place the second cake layer on top.
10. Chill & Finish with Flair: Pop the cake into the refrigerator for at least 30-45 minutes; this helps the inner caramel layer set. After chilling, spread the remaining frosting evenly over the top and sides of the cake. For a final flourish, garnish with your toasted pecans and an extra drizzle of salted caramel. Slice and enjoy this truly special, homemade treat!