Buttermilk Cake with Dulce de Leche Praline Filling and Cream Cheese Chocolate Frosting

For the buttermilk cake:

1. Preheat oven to 350ºF / 180ºC. Butter and flour or spray a 9inch (24cm) round springform cake pan.
2. Sift flour, baking powder and soda, and salt. Reserve. Mix buttermilk and vanilla in a small bowl or glass cup.
3. In a large bowl beat butter until creamy, about 1 minute. Gradually add sugar, and beat for 4 or 5 minutes, until very light. Scrape down the sides of the bowl with a spatula as needed.
4. Add eggs, one at a time, and beat until smooth between additions. Beat for 1 minute after adding the third egg.
5. Add dry ingredients in three additions, alternating with liquids in two additions. Don't beat this too much, it should only be mixed until well blended. Over beating will make the cake tough.
6. Pour into prepared pan and bake for for 40 to 45 minutes, until a tester inserted in center comes out clean.
7. Let cool on wire rack for 15 minutes and inverto onto a rack and let cool completely before filling and frosting.
8. Cut the cake in half, trying to cut it as even as possible. To achieve this, start by using a large thin knife, and cut while rotating the cake. With each turn, the knife should go deeper, until you reach the center. At that point the cake will be completely cut in half.
9. Spread dulce de leche on top of one half, spreading evenly but without touching half an inch from the edge. (That way, when you press the second layer on top, the dulce de leche will reach the edges but not spill).
10. Add half of praline on top of dulce de leche. Top with the other cake layer, press lightly and frost with chocolate frosting.
11. The best way to frost is to take about half the frosting and make one layer covering the whole cake. Then take the rest of the frosting, and even it out as best as you can.
12. Sprinkle remaining praline on top and serve.

For the hazelnut praline:

1. Melt sugar in a medium saucepan over medium heat. Stir a few times as it starts to melt.
2. It will clump at first. Then it will start turning golden, at which point stir it some more to prevent it from burning in spots.
3. Finally the whole of the sugar will melt and the liquid will be a deep amber color. Be very careful because it goes from deep golden to burnt just like that.
4. Immediately add hazelnuts, stir to coat all of them in the caramel and dump onto a silpat or oiled surface, such as marble or baking tray. Let cool.
5. Try to break praline as much as you can. Then place between two sheets of waxed paper, and with a rolling pin, break into small pieces.
6. Transfer these pieces to the food processor and process until finely ground. Some larger pieces will remain.

For the chocolate frosting:

1. Melt both chocolates on top of a double boiler or in the microwave. Be careful not to burn it.
2. Let cool until lukewarm, then add to the room tº cream cheese.
3. Add the salt and beat with an electric mixer until very smooth and shiny.