Three-Layer Caramel Cake

Step 1
Preheat oven to 350 degrees F (175 degrees C). Grease three 9-inch cake pans.

Step 2
Combine flour, canola oil, white sugar, buttermilk, eggs, vinegar, baking soda, 1 teaspoon vanilla extract, and cocoa powder in a large bowl. Mix until evenly distributed, 2 to 5 minutes. Pour batter evenly into the prepared cake pans.

Step 3
Bake in the preheated oven until golden brown, about 20 minutes. Remove from oven and let cool, about 30 minutes.

Step 4
Combine sweetened condensed milk, dark brown sugar, butter, 2 teaspoons vanilla extract, and salt in a saucepan over medium heat. Bring to a boil. Stir constantly until frosting is thick, 3 to 5 minutes. Let cool, about 5 minutes.

Step 5
Remove cooled cakes from pans. Spread frosting onto the cooled cake layers. Stack layers; frost top and sides.