For the Swedish Princess Layer Cake

First, Make The Pastry Cream:

• Make the pastry cream. In a medium, heavy-bottomed saucepan, whisk together the milk, egg yolks, sugar, cornstarch, and salt. The mixture will be a little lumpy, but that's okay, I promise!

  Bring to a boil over medium-low heat, and cook, whisking continuously, until the mixture thickens enough to coat the back of a spoon, 1 to 2 more minutes.

  Remove from the heat. Immediately add the butter, almond, and vanilla extracts and whisk until smooth. Place a fine-mesh sieve over a small bowl and pour the pasty cream through the sieve to remove any lumps. Set the bowl on a wire rack and let cool completely before using in the recipe or storing for later use.

  To store, pour the pastry cream into an airtight container and press a sheet of plastic wrap directly against the surface of the pastry cream to prevent a skin from forming. Cover with a lid and refrigerate for up to 1 week.

Next, Make The Cake:

• Prep the oven and pans. Position a rack in the center of the oven and preheat the oven to 350°F.  Generously spray two 6-inch cake pans with cooking spray and line the bottom of each with a parchment paper circle. Spray the parchment, too.
• Mix the dry ingredients. In a medium bowl, whisk together the flour, sugar, baking powder, and salt.
• Whisk the wet ingredients, then mix in the dry ingredients and hot water. In a large bowl, whisk together the sour cream, oil, egg, and vanilla.

  Gradually whisk in the dry ingredients until just combined. The mixture will be thick, but that's okay, I promise!

  Slowly pour in the hot water. Use the rubber spatula to finish mixing until smooth and well combined, 1 to 2 minutes more.
• Divide the cake batter between the pans. Divide the batter evenly between the pans; if using a digital scale to measure out layers, note that this recipe makes around 24 ounces (680 grams) of batter—pour 12 ounces (340 grams) of batter into each cake pan.
• Bake and cool the cakes. Bake for 30 to 35 minutes. When done, the top of the cake should bounce back when gently pressed and a skewer inserted into the center of the cake should come out with a few crumbs attached. Cool completely in the pans on a wire rack before frosting.

Prepare to Assemble The Swedish Princess Layer Cake:

• Once the pasty cream is chilled, the cakes are cooled, and you're ready to assemble the cake, make the whipped cream. In the bowl of a stand mixer fitted with the whisk attachment, combine the cream and confectioners' sugar. Whisk on medium-high until firm peaks form, 3 to 5 minutes.
• Dye the marzipan. Place a sheet of parchment paper on the counter and dust with confectioners' sugar. Add 1 to 2 drops of green food coloring into the center of the marzipan and knead until completely combined and pale green.
• Shape the marzipan. Place a second sheet of parchment paper on top of the marzipan and use a rolling pin to roll it out to a 6-inch wide, ⅛-thick circle.

Assembly:

• Prep the cake ring and acetate cake collar. Clean the cake ring and place it in the center of a sheet pan lined with clean parchment paper. Line the inside of the cake ring with the acetate paper (if using two strips of acetate paper, just use one strip).
• Build the Swedish princess layer cake. Set one of the cake rounds in the lined cake ring.

  Use the back of a spoon or a small rubber spatula to spread the pastry cream on top of the cake. Then, spread the jam over the pastry cream.

  If you're using two acetate cake collars, gently tuck the second strip of acetate between the cake ring and the top ¼ inch of the first strip of acetate. Doing so creates a ring of acetate that is 5 to 6 inches tall, combined—this will be high enough to support the height of the finished cake.

  Set the second cake round on top of the jam. Spoon the whipped cream over this cake round, spreading it to create an even layer on top of the cake. Carefully set the marzipan round on top of the whipped cream.
• Chill the cake. Transfer the sheet pan with the cake to the refrigerator. Chill, uncovered and fully assembled, for a minimum of 2 hours to set the cake and all its fillings.
• Serve and store. When you're ready to serve the cake, pull the sheet pan out of the refrigerator and use your fingers and thumbs to gently lift the cake ring out from around the cake. Transfer the cake to a serving plate or cake stand. Gently peel off the acetate.

  Serve immediately. The assembled cake will keep, uncovered in the refrigerator, for up to 1 day. After that, tightly wrap in plastic wrap and refrigerate for an additional 3 days. Leftover slices can be stored in an airtight container in the fridge.