Cake Layer Dough:

1. Combine the flour and salt on the counter or food processor. Add the cold butter, cut into chunks, into the flour and use a knife to work it into the flour, until there are pea sized bits of butter throughout the dough.
2. In a medium bowl or large mixing cup, whisk the water, vinegar, vodka, and beaten eggs until evenly mixed. The vinegar and the vodka help to make the cake layers really tender and flaky. The vodka gives the dough more liquid and makes it easier to work with and roll out, but when the cake layers bake, the vodka will cook out, which makes the cake layers more crisp. You won’t be able to taste the vinegar or vodka in the cake at all.
3. Make a well in the center of the flour on the counter and pour in the liquid ingredients. Gently but quickly mix the dough, just until it comes together. Knead just a little, working the flour into the dough. Work as quickly as you can, so that the chunks of butter don’t completely melt into the dough. The chunks of butter will melt as the cake layers bake and will form air pockets in the cake layers and give them that wonderful thin, flaky, puffed texture.
4. Form the dough into a disc shape. Wrap the dough into parchment paper or aluminum foil and place it into the refrigerator. Chill for a few hours or overnight.
5. Make the pastry cream. Follow the instructions in this post. The recipe is slightly different, but the technique is exactly the same, so use the ingredient amounts from this post, following the instructions in the other post.
6. Chill the pastry cream in the refrigerator until completely cool, a few hours or overnight.
7. I usually make the cake layer dough and the pastry cream the day before I am planning on making the cake.

Baking the Cake Layers:

1. Preheat the oven to 400 degrees Fahrenheit. Prepare 2 large rimmed baking sheets, so you can bake the cake layers quicker, if you interchange them, putting one in the oven, rolling out the next layer and then immediately putting it into the oven as soon as the first layer bakes and so on. Also prepare 10-12 pieces of parchment paper as big as the baking sheet.
2. Divide the dough into 10-12 layers. If you want an 8-9 inch cake, you will probably end up with 12 cake layers. If you want the cake to be 10 inches, you will have 10 cake layers. Also, I often make 2 smaller, shorter cakes out of this recipe, instead of one large, tall cake. In which case, you will have 2 (8-9 inccakes that are 6 layers high, and 2 (10 inch cakethat are 5 layers high. You can easily halve the recipe for this cake.
3. Roll out each portion of cake dough right on top of a piece of parchment paper, sprinkling a bit of flour on it before rolling out the cake layers. Roll out thin circles.
4. Place a 8-10 inch round plate, cake pan, springform pan, etc. on top of the rolled out dough.
5. Use a small paring knife to cut out an 8-10 inch circle, all around the outside of the circular object that you are using. Leave the dough remnant just where they are. Transfer the rolled out cake layer along with the parchment paper to the prepared baking sheet. Use a fork to prick some holes all over the center of the cake layers to keep them from puffing up unevenly.
6. Bake in the preheated oven for about 8 minutes, until lightly golden.
7. Repeat will all the cake layers. Set aside to cool. Save the cake dough scraps that baked along with the cake layers. You will use those later as crumbs to decorate the cake.

Pastry Cream Frosting:

1. Before you start making the frosting, make sure the pastry cream and the butter are both at room temperature. If one or the other is too cold, the frosting will not be smooth and consistent, but will have a curdled appearance, with bits of butter flecks throughout the frosting that you will not be able to fix.
2. In a large bowl or a standing mixer a using a hand mixer, cream the butter, powdered sugar and vanilla extract, mixing until smooth and fluffy.
3. Add the pastry cream, a few heaping Tablespoons at a time, mixing on low speed, gradually increasing to medium speed, until all of the pastry cream is incorporated into the buttercream.
4. In a separate bowl, whip the heavy cream until soft peaks form. Fold in the whipped cream into the pastry cream.

Assembling the Cake:

1. Line your edge of your serving plate/cake stand with aluminum foil. This is a trick I use to keep the edge of the plate clean. Place a dollop of frosting into the center of the plate, just to keep the cake from sliding around.
2. Top each cake layer with a generous amount of frosting and spread it around evenly. You will need to use all of the frosting for the cake, so divide it evenly between all the cake layers. The frosting should be approximately the same thickness as each cake layer.
3. Repeat will all the cake layers and frosting.
4. Smooth out the frosting over the sides and top of the cake. Place the cake layer scraps into a large ziplock bag. Use your hands or a rolling pin to crush them into fine crumbs. Press the crumbs over the sides of the cake and sprinkle them evenly over the top of the cake. Keep it simple like that, or decorate with fresh berries, chocolate shavings, nuts, etc.
5. Gently pull out the aluminum foil out from underneath the cake.
6. It is best to refrigerate the cake overnight, so that the frosting soaks into the cake layers and gets really soft and tender. It will get slightly shorter as the frosting seeps into the cake layers.
7. Keep the cake refrigerated. It helps to let it stand a room temperature for 30 minutes or so before serving.