Preheat oven to 350°F / 175°C. Lightly grease a nonstick hot dog-bun pan.

In a large bowl, whisk together the flour, ½ cup / 100g of the sugar, baking powder, and salt until combined. Set aside.

In a separate bowl, stir together the egg yolks, oil, orange juice, orange zest, and vanilla.

Add the dry ingredients to the egg yolk mixture and whisk together until smooth. Set aside.

In a stand mixer fitted with the whisk attachment, combine the egg whites (5 total) and cream of tartar and beat on high speed until medium peaks form, about 2 minutes.

Turn the speed to medium-low and slowly sprinkle the remaining ¼ cup / 50g sugar to create a French meringue. Turn the speed to high and beat until stiff, glossy peaks form, 1 to 2 minutes more.

Stir ⅓ of the meringue mixture into the egg yolk mixture to loosen it up. Then, fold the remaining meringue into the yolk mixture.

Fit a 16-inch / 40cm pastry bag with a large round tip (Ateco #9807), pour the batter into the bag, and then pipe into the prepared pan, filling each mold only ⅔ full.

Bake until golden and a tester comes out clean, 15 to 20 minutes. Invert the pan and tap gently to remove the cakes onto a sheet of parchment paper. Let cool completely.

In a stand mixer fitted with the paddle attachment, combine the confectioners’ sugar and butter and beat on low speed until combined.

Turn the mixer speed to medium and beat until a thick paste forms. Scrape down the bowl and paddle, then add the vanilla, almond extract and salt and beat for a few seconds more.

With the mixer on low speed, add enough of the cream, a little at a time, to make the frosting spreadable. Use immediately.

Fit a 12-inch/30-cm pastry bag with a Bismark piping tip (Ateco #230) and fill with the frosting. Inject the frosting from the bottom of each cake by poking the tip into it about ¾ of the way through—fill until the cake begins to bulge. Repeat injecting the frosting every ½ inch / 1.3 cm.

Serve the cake immediately or store in the refrigerator, covered, up to 24 hours. If refrigerated, bring the cake to room temperature before serving.