• Preheat the oven to 350 degrees F. Spray two 9x2 -inch metal cake pans with flour-added baking spray or grease with shortening and dust with flour. Line pans with parchment circles if desired. Alternatively, use a 9x13 inch pan.
• Mix together the flour, baking powder and salt and set aside.
• In a stand mixer bowl, beat the butter on medium high speed until light and creamy. Beat in the vanilla. Gradually add the sugar, scraping the sides of the bowl once or twice and beating for about 5 minutes or until light and creamy.
• Add eggs one at a time and continue beating for another minute or two, scraping sides of bowl.
• Reduce speed to low and add the milk, then add flour and sour cream alternately. When flour is fully incorporated, divide evenly among the pans.
• Bake on center rack for about 35 minutes or until cakes spring back when touched and a pick inserted comes out clean.

Caramel Frosting

• Start by gathering your pans. You're going to need a small stainless steel skillet or saute pan to caramelize the sugar, a Dutch oven or 4 to 5 quart heavy saucepan, and a stand mixer with the paddle attached. You'll also need one large clean mixing size bowl.
• To get started, put ⅔ cup (130 grams) of the sugar in your stainless steel pan and set it aside.
• The next step, put 1 cup of cream, 2 tablespoons of corn syrup and 2 ⅓ cups sugar in the large pot or Dutch oven. Set it over medium heat and cook, stirring with a heavy duty heat proof scraper, for about 7 minutes or until sugar is dissolved. Remove it from the heat, cover and keep warm while you make the caramelized sugar.
• Set the pan with the sugar over medium heat and cook without stirring until it starts to glisten. Begin looking for signs of melting sugar. At this point, agitate the sugar with a wooden spoon or heat-proof scraper, stirring and tilting and watching it go from clear to a deep amber. Once deep amber, scrape it into the warm cream mixture. Be careful because it will bubble up a little.
• Set the mixture over medium heat. Cook and stir over medium heat until mixture hits 238F on an instant read or deep fry thermometer. I like to use a deep fry thermometer for this. Immediately pour it into the stand mixer bowl.
• Add butter and vanilla and stir just until butter is melted and blended in. Let mixture cool down to 110 F. This should take about 45 minutes to an hour.You can use an instant read thermometer or just leave your deep fry thermometer in the bowl.
• When mixture reaches 110 F, set the stand mixer bowl on the mixing station and beat with the paddle for 10 minutes until mixture cools to 90 degrees F. Add about a tablespoon of cream to help cool it down and thin it out if needed. At 90 degrees. scrape into another clean bowl and let cool to 75 degrees F. at which point it should be smooth and spreadable.