Preheat oven to 350° F. Grease or line with parchment paper, 2, 8 in cake pans.

Sift together flour, corn starch, baking powder, and salt. Use a whisk or fork to blend together thouroughly. Set aside.

In a large bowl combine butter, oil, sugar, and brown sugar. Use a mixer to cream together about 2 min. until light and creamy.

Add eggs in, 1 by 1, mixing well in between. Add yogurt and vanilla, mix well.

With a mixing spoon or spatula, fold in half the dry ingredients to the wet mixture. Do minimal mixing until just combined to keep the cake soft. Add milk and minimally mix. Add the remaining ingredients and minimally mix.

Distribute batter evenly into the cake pans. Bake for 25-30 min. Test with a toothpick before removing from oven.

Allow them to cool for about 15 min. Remove them from pans to finish completely cooling before frosting.

Frosting

In a large saucepan, over medium heat, add butter, sugar, evaporated milk, and salt. Bring it to a simmer, stirring continuously. Once simmering, lower heat to low-medium.

Allow the caramel to thicken slowly for about 1 hr, stirring every few minutes to keep it from burning/overcooking on the bottom. It needs to be checked more frequently as it thickens.

Once the mixture is thick and a deep golden brown, add the cream and vanilla. Mix well, until smooth and creamy, then pour into a heat safe bowl to cool.

After cooling for about 20-25 min (needs to be slightly warm and runny).

Assembly

Level cooled cakes with a serated knife so the tops are flat and even.

Place the bottom layer on the serving dish. Put a generous layer of caramel frosting on that layer. Smooth it with a spatula or knife.

Place the top layer cake onto the bottom layer. Frost the top and sides until covered to your liking. Wait for it to set before serving. It will look shiny. If you want it smoother, use spatula or knife again to smooth before serving.