01 -
Combine granulated sugar and water in a medium saucepan, stir until the sugar is evenly moistened. Spread into an even layer and heat over medium-high until the sugar dissolves and begins to turn golden. Stir occasionally as it browns evenly.
02 -
Once the caramel reaches a golden amber color, reduce to medium heat. Stir in butter until melted, then gradually add heavy cream, stirring constantly as the mixture bubbles vigorously. Incorporate a pinch of salt, mix until smooth, then transfer to a shallow bowl and chill in the refrigerator until cooled to room temperature.
03 -
Preheat oven to 170°C (conventional). Line three 20 cm round baking pans with parchment paper.
04 -
Sift together all-purpose flour, cornstarch, baking powder, baking soda, and salt in a medium bowl. Set aside.
05 -
In a large mixing bowl, beat butter and granulated sugar using a mixer on high for 3 minutes until pale and fluffy.
06 -
Add eggs two at a time, mixing until just incorporated. Scrape down the bowl as needed.
07 -
Add half the sifted dry ingredients and mix on low until nearly combined. Add sour cream, vegetable oil, and vanilla extract, mixing until just blended. Incorporate remaining dry ingredients and mix until no flour streaks remain. Fold the batter gently with a spatula.
08 -
Divide batter evenly among prepared pans and smooth the tops. Bake for 19–22 minutes, or until a cake tester inserted in the centre comes out clean and the cakes remain pale in color. Cool cakes in the pans for 10 minutes, then remove and cool completely on a wire rack.
09 -
Place butter in a stand mixer fitted with the paddle attachment. Beat on medium-high for 4 minutes. Scrape down the bowl, then beat for 2 more minutes. Gradually add sifted powdered sugar, vanilla extract, and salted caramel in two additions, beating until fully incorporated. Mix on low for 1 minute to finish.
10 -
Place one cake layer on a serving plate or turntable. Spread a generous layer of caramel buttercream over the surface. Drizzle 2–3 tablespoons salted caramel on top and gently spread, leaving a border to prevent caramel from spilling out. Repeat with remaining cake layers.
11 -
Cover the assembled cake with a thin layer of buttercream to trap crumbs. Chill in the refrigerator for 20 minutes until set.
12 -
Cover the cake with the remaining buttercream, smoothing evenly around the sides and top. Optionally, swirl extra caramel on top for a decorative effect. Slice and serve.