preheat the oven to 350ºf. turn an 8” square baking pan into a battenberg pan: first, fold a long piece of foil onto itself a couple of times to a create a foil barrier to divide your pan in half, making sure that the barrier is at least the height of the pan or even a little more. then spray the pan and each side of the foil with cooking spray (to help the parchment stick) and line each half of the pan with two overlapping pieces of parchment paper, one going widthwise and one going lengthwise, with enough parchment paper to come all the way up the sides and then some. get your scissors out and trim the parchment so that it lays nicely and doesn’t curl around the corners and make you go crazy. sorry, i know this is a lot of parchment paper (i reuse parchment all the time!). ok, set this aside.
in a medium bowl, sift together the flour and baking powder, and then lightly stir in the salt and set aside. in a large measuring cup, whisk together the heavy cream and sour cream and set aside.
in a stand mixer fitted with a paddle, cream together the butter, coconut oil, and sugar on medium high for 3-4 minutes, until light and fluffy. add the eggs, one at a time, beating well after each and periodically scraping the sides of the bowl with a rubber spatula. add the vanilla and rosewater and mix to combine. reduce the mixer to medium low and add the dry mixture and cream mixture in 3 alternating additions, mixing until 80% combined. divide the mixture in half. in the first half, fold in the sprinkles as you mix until the batter is combined. pour into one side of the pan and use a small offset spatula or a spoon to carefully spread it out evenly. in the second half of the batter, add a few drops of pink food coloring and fold it in as you mix until the batter is combined. pour into the other side of the pan and use a small offset spatula or a spoon to carefully spread it out evenly. bake until the tops of the cakes are browned and a toothpick inserted into the center comes out with a few crumbs on it; begin checking for doneness at 45 minutes. let cool in the pans for 10 minutes and then use the parchment wings to left them out of the pans and onto a wire rack to cool completely.
once the cakes are cooled, level them and trim off the sides if they’re uneven. cut into 4 equal rectangles that are as wide as they are thick (measure the thickness of the cake once it’s leveled and then turn your ruler 90º to measure that same amount on top of the cake and score with an accordion pastry cutter). enjoy a bite of cake scraps and set these aside.
knead the marzipan with food coloring to get your desired color, dusting with powdered sugar if it gets too sticky. on a silicone mat (or a big piece of parchment or a counter dusted with powdered sugar, but i strongly recommend a silicone mat so that you don’t get powdered sugar all over what will eventually become the outside surface of the marzipan) roll the marzipan out into a rectangle that’s about 7 1/2” wide by about 13” long, dusting the top with powdered sugar as needed to prevent sticking. trim the edges so they’re straight. brush all over with a thin layer of jam and place a rectangle of pink cake at one end. brush the exposed surfaces with a thin layer of jam. squish a rectangle of sprinkle cake right next to it and brush the exposed surfaces with a layer of jam. stack the other two rectangles of cake on top, brushing with jam, to form a checkerboard pattern. carefully roll it onto its side, pressing the marzipan all over so that it sticks, and then continue to roll until the cake is covered. trim off any excess marzipan, wrap in firmly plastic wrap and let set in the fridge for a couple of hours. decorated with additional marzipan decorations and sprinkles as desired. let come to room temperature and enjoy!
this cake will last at room temperature, wrapped in plastic or in an airtight container for up to a week.