Preheat oven to 375 degrees. Generously spray both sides of the cake mold with baking spray and dust liberally with granulated sugar (yes, sugar, not flour. Trust me). Shake out excess sugar if necessary.
Whisk together the flour, baking powder, and salt in a small bowl and set aside.
In the bowl of a stand mixer fitted with a paddle attachment cream together the shortening and the sugar until light and fluffy, about 5 minutes.
Meanwhile, in a separate bowl with a hand mixer or whisk, whip the egg whites until thick enough to hold stiff peaks, set aside.
Add the egg yolks to the sugar mixture, one at a time, mixing well until fully incorporated, scraping down the bowl again as necessary. Stir in the vanilla extract.
Working in three batches, add the dry ingredients and stir to combine, alternating with an addition of milk (so, it should go flour-milk-flour-milk-flour). Just before batter is completely mixed, gently fold in egg whites, being very careful not to deflate batter.
Place the front end of the cake mold face side down on a baking sheet. Fill with all of the cake batter (it’s going to be really full, y’all). Place toothpicks inside the batter along the lambs ears, head, and neck for added support.
Place the back half of the cake mold over the top to seal. Tie together with butcher’s twine in a few places to ensure the mold will stay together (if you have one of the fancy cast iron ones that weighs a few pounds, this step isn’t totally necessary).
Wrap the head of the cake mold in a layer of aluminum foil and the ears in a second layer of foil before baking in preheated oven for 45 – 55 minutes. Yes, there is no way to tell if the cake is done, you can’t peak, you can’t check, you can’t test. Truly, you just have to go with your gut. Oven temps vary – mine typically hitting at 52 minutes, though I’ve taken it to 55 for a very golden brown cake.
When you feel ready, remove the cake from the oven (if there’s been a little cake batter overflow, don’t mind it, that’ll come off no problem). Cool cake in mold on a wire rack for about one hour, or until just barely warm to the touch.
Remove foil helmet and butcher’s twine. Starting from the bottom of the mold, gently press the front end of the mold into the cake (and away from the outer, back half, of the mold, to release the cake at the seam). Continue all the way around the mold to begin releasing the cake. At this point, you should feel the cake loosen and become free from the back half of the mold. Remove the back half of your mold. Flip cake over on the cooling rack and gently pry the front of the mold from the cake. Behold the beauty you have created.
Cool cake completely on wire rack. (It’s at this time you should notice the beautiful crust created from the coating of granulated sugar!)