This salted caramel cake has three fluffy vanilla cake layers filled with salted caramel sauce and frosted with a whipped caramel cream cheese frosting.
Prep: Preheat your oven to 180°C (350°F). Line three 8-inch round cake pans with parchment paper.
Cream the Butter: In a large mixing bowl, beat the softened butter, sugar, salt, and vanilla extract with an electric mixer until creamy and smooth, about 3 minutes.
Add the Wet Ingredients: Add the vegetable oil, sour cream, and vinegar, and mix until creamy.
Add the Eggs: Add the eggs one at a time, mixing well after each addition.
Dry Ingredients: In a medium bowl, whisk together the flour and baking powder.
Combine: Add half of the dry ingredients and the milk to the batter and mix until almost combined. Add the remaining dry ingredients and mix just until combined.
Bake: Divide the batter evenly between the three pans. Bake for 25 to 30 minutes, until a toothpick inserted into the center comes out clean. Cool completely before assembling.
Make the salted caramel sauce
Combine: In a medium stainless steel saucepan, combine the sugar, water, and corn syrup. Stir with a wooden spoon until the sugar is nearly dissolved.
Simmer: Turn the heat to medium and bring the mixture to a simmer. From this point on, do not stir the caramel.
Brush the Sides: Brush the inside walls of the saucepan with a wet pastry brush to wash away any sugar crystals and prevent graininess.
Watch the Color: Cook until the syrup turns from clear to a deep amber, the color of a copper penny.
Add the Butter: Remove from the heat immediately and carefully whisk in the room temperature butter until melted.
Add the Cream: Slowly pour in the room temperature heavy cream, vanilla extract, and salt while whisking constantly. The caramel will bubble up, so pour carefully.
Thicken: Return the saucepan to medium heat and cook for 2 minutes, stirring constantly. Remove from the heat and let the caramel cool completely to room temperature. It will thicken as it cools.
Make the caramel frosting
Beat the Cream Cheese: In the bowl of a stand mixer, beat the room temperature cream cheese, powdered sugar, vanilla extract, and instant pudding mix until smooth and lump free.
Whip: With the mixer running on low, slowly pour in the cold heavy cream. Increase the speed to medium-high and whip until thick and stiff peaks form.
Add the Caramel: Add the salted caramel and whip briefly, just until combined.
Assembly
First Layer: Place the first cake layer on a cake board or serving plate. Pipe a ring of frosting around the edge of the layer to create a dam, then fill the center with salted caramel sauce.
Stack: Top with the second cake layer and repeat with another frosting dam and caramel filling. Top with the third cake layer.
Frost: Cover the top and sides of the cake with the remaining caramel cream cheese frosting and smooth it with an offset spatula.
Caramel Top: Spread more salted caramel sauce over the top of the frosted cake and make waves with an offset spatula. Sprinkle with flaky salt and chill for at least 30 minutes before slicing.
Notes
Room Temperature Ingredients: Use room temperature butter, eggs, sour cream, and milk for the cake so the batter mixes into a smooth, even mixture.
Measure Flour Correctly: Spoon the flour into your measuring cup and level it off, or use a kitchen scale. Scooping packs in extra flour and makes the cake dry.
Caramel Safety: Use room temperature butter and cream for the caramel and pour slowly. Hot caramel bubbles up and can splatter.
Don’t Stir the Caramel: Once the sugar mixture simmers, don’t stir it. Brush the sides of the pan with a wet pastry brush to prevent graininess.
Cool the Caramel: Let the caramel cool completely to room temperature before using it in the frosting or filling. Warm caramel will melt the frosting.
Cold Cream, Soft Cream Cheese: The heavy cream must be very cold to whip into stiff peaks, and the cream cheese should be soft so the frosting stays smooth and lump-free.
Frosting Dam: Pipe a ring of frosting around the edge of each layer before adding the caramel so the filling stays in place.
Chill Before Slicing: Chill the finished cake for at least 30 minutes so the frosting and caramel set and the slices come out clean.
Storage: Keep the cake in the refrigerator for up to 4 days. Take it out 15 to 20 minutes before serving.