SALTED CARAMEL

• In a medium saucepan, add the granulated sugar and water and stir it together so all of the sugar is wet. Flatten it out into an even layer, so it melts evenly. Melt it over medium/high heat until golden brown. Once you can see it starts slightly brown, give it a stir once in a while so it all melts evenly.
  140 g granulated sugar, 1 ½ tablespoon water
• Once the caramel is golden brown, reduce the heat to medium heat and stir in the butter until it has melted into the caramel. Then add the heavy cream, a little at a time, stirring in each addition until incorporated. It will bubble up strongly so be careful of your fingers. Stir constantly until it has gathered.
  40 g butter, 150 g heavy cream
• Turn off the heat and add a pinch of salt. Transfer it to a shallow bowl, so it can cool down faster, and let it cool down in the fridge. It takes about 30-60 minutes to become room temperature.
  big pinch of salt

VANILLA CAKE LAYERS

• Preheat the oven at 170ºC/340ºF conventional oven and prepare a 3 x20 cm baking pan with parchment paper.
• Sift together the all-purpose flour, cornstarch, baking powder, baking soda and salt and set it aside.
  340 g all-purpose flour, 2 tablespoon cornstarch, ¾ teaspoon baking powder, ¾ teaspoon baking soda, ¾ teaspoon salt
• In a large mixing bowl add the granulated sugar and butter and mix it together on high speed for 3 minutes.
  180 g butter, 300 g granulated sugar
• Add the eggs two at a time into the mixture and mix it in until combined.
  4 large eggs
• Continue by adding half the dry ingredients, on low speed, mixing until just combined.
• Then add the sour cream, vegetable oil and vanilla extract and mix until just combined. Then add the other half of the dry ingredients and mix until combined.
  240 g sour cream 14-18%, 60 g vegetable oil, 2 teaspoon vanilla extract
• Using a rubber spatula, give the batter a gentle fold to make sure all of the ingredients have combined.
• Divide the cake batter into the prepared pans and bake for 19-22 minutes or until a cake tester comes out clean. They will stay light and won’t brown. 
• Let the cakes cool on a cooling rack. After 10 minutes, gently remove the cakes from the cake tins and let the cakes cool down completely.

CARAMEL BUTTERCREAM

• Sift the powdered sugar and set it aside.
  660 g powdered sugar
• Mix the butter in a stand mixer with the paddle attachment or with a hand mixer for 4 minutes on medium/high speed. Scrape down the sides of the bowl and mix for an additional 2 minutes.
  400 g butter
• Add the powdered sugar, vanilla extra and caramel in 2 parts. Whipping until each addition is fully incorporated.
  2 teaspoon vanilla extract, 2-3 tablespoon caramel
• Scrape down the sides of the bowl and give the buttercream a final mix for 1 minute on low speed.

ASSEMBLING

• Place the first cake layer on your serving dish or cake board on your turntable. If you don’t have a turntable, don’t worry, you can easily decorate the cake without it.
• Add 2 big scoops of buttercream and with an offset spatula, even it out. Then add 2-3 tablespoon of caramel and even it out. Leave the outer edge of the cake free so the caramel doesn’t spill out. Repeat the process for the next cake layer. Add the last cake layer and cover the whole cake in a thin crumb coat.
• Place it in the fridge for 20 minutes, so it’s easier to cover the whole cake in the remaining buttercream.
• Add the remaining frosting, and even it out over the cake. Finally, add as much of the remaining caramel on top of the cake as you’d like. Optionally, swirl the caramel into the buttercream for a pretty design.

The US customary cup measurement serves as a rough estimate, as it can have uncertainties, so for precise results, it's recommended to weigh your ingredients using a digital scale in grams. Baking is both an art and a science, which most often requires precision and accuracy.