Ingredients

1. 1 3/4 cups (210g) all-purpose flour, spooned and leveled
2. 3/4 cup (60g) Dutch-process cocoa powder, spooned and leveled
3. 1 Tbsp (10g) baking powder
4. 1/2 tsp salt
5. 1/4 cup (56g) unsalted butter, room temperature
6. 1/2 cup (118mL) canola oil
7. 1 1/2 cup (300g) granulated sugar
8. 3 large eggs, room temperature
9. 2 tsp vanilla extract
10. 3/4 cup (170g) sour cream
11. 3/4 cup (180mL) milk, room temperature
12. 1 cup (200g) granulated sugar
13. 1/4 cup (59mL) water
14. 1/2 cup (118mL) heavy cream, room temperature
15. 1/4 cup (56g) unsalted butter softened
16. 1/2 tsp salt
17. 1 1/2 cups (340g) butter, room temperature (not greasy soft)
18. 1 can (14oz) Eagle Brand Sweetened Condensed Milk
19. 1/2 cup (40g) Dutch-process cocoa powder, spooned and leveled
20. 1 tsp vanilla extract

Instructions

1. Place the sugar and water in a medium size heavy bottom sauce pan. Swirl the pan until the sugar is immersed in water. Place the saucepan over medium heat and allow the sugar to fully dissolve in the water, gently swirling the pan every minute or so.
2. Bring the sugar and water to a simmer and lower the heat to low. Place the lid on the pan and allow the mixture to simmer until the color begins to darken to a light amber color, this should take about 10 minutes. Make sure to remove the lid and check the color at least every minute.
3. You can gently swirl the pan every couple of minutes but DO NOT STIR IT WITH ANYTHING. If there are crystalized pieces of sugar on the sides of the pan, the steam running down from the lid should dissolve them but if it doesn’t, you can use a pastry brush wet with water to brush them away.
4. Once the sugar is a dark amber color, remove it from the heat. Stir in the butter until it’s melted, then add the heavy cream, whisking until the caramel is smooth. 
5. Pour the caramel sauce in a heat proof jar and stir in the salt and vanilla extract.
6. Allow it to cool until it’s not piping hot, about an hour. Refrigerate until the caramel is set. 
7. If you’ve never made caramel sauce, make sure to read my whole post on homemade salted caramel sauce. 
8. Begin by bringing all your ingredients to room temperature. Preheat the oven to 350°F (177°C) convection (325F/163C conventional) and grease and line three 6 inch cake pans with baking spray and parchment paper.
9. In a medium bowl, whisk together the flour, cocoa powder, baking powder and salt until they’re evenly distributed. Set aside.
10. Place the room temperature butter and the granulated sugar in a large bowl and use an electric mixer with the whisk attachment to beat them for 1-2 minutes. Add the oil and beat for another 1-2 minutes.
11. Add the eggs, one at a time, beating on medium speed until each egg is fully incorporated, about 30-60 seconds between each egg. Add the sour cream and vanilla and beat just until it’s combined.
12. Add half of the dry ingredients to the batter, turn the mixer to low speed and then stream in the milk, followed by the rest of the dry ingredients.
13. Distribute the batter evenly among the three cake pans, about 14 ounces in each pan, and bake for 30-35 minutes. When the cake is fully baked it will release itself from the edge of the pan and it will spring back if you press on the center of it.
14. Remove from the oven and invert them onto a tea towel or cooling rack. Allow them to cool completely before frosting.
15. Make sure to read my 6 inch chocolate cake post if you haven’t made them before.
16. To make the frosting, use the stand mixer and whisk attachment at full speed to whip the butter for 10 minutes, until pale and fluffy. Scrape the bottom and sides of the bowl every few minutes.
17. Lower the speed to medium and slowly pour in the Eagle Brand Sweetened Condensed Milk, scraping the bottom and sides of the bowl as needed.
18. Add the cocoa powder and vanilla and beat until they’re well combined. If the frosting is too soft to use, refrigerate for about 30 minutes, mixing it every 10 minutes or so.
19. Place the frosting in a piping bag fit with a round tip. Pipe a boarder of icing on the edge of the first layer of cake, fill the border in with a layer of cooled caramel sauce and then pipe another thin layer of frosting on top of the caramel.
20. Refrigerate the cake for 15 minutes and repeat with the second layer. Then refrigerate the cake for another 15 minutes, place the last layer of cake on top. Refrigerate the cake for 30-60 minutes before frosting the outside.
21. Use the rest of the frosting to frost the outside of the cake. Drizzle extra caramel on top.
22. Serve immediately or store in the refrigerator.