
Pre-heat the oven to 180C (350F) static. Grease the bundt pan with butter, then lightly dust it with flour, shaking off any excess.
Add 2 whole eggs and 2 egg yolks (reserve the whites for the topping) to a stand mixer with the caster sugar (150g|/3/4 cup). Whisk on a medium speed until thick and pale.
Add the melted butter on a low speed and then add the alchermes liqueur (see notes for substitution).
Once incorporated, add the lemon zest. Combine the baking powder and flour together with a pinch of salt, and add it to the cake batter a spoonful at a time on medium speed until a smooth batter forms.
Pour the batter into the prepared Bundt pan and smooth out the surface. Bake on the middle shelf for 30-35 minutes or until a toothpick inserted comes out clean.
10 minutes before the cake is done, add the 2 reserved egg whites to the clean mixer. Whisk the whites until white and frothy, then add the caster sugar and powdered sugar gradually, a spoonful at a time, until combined. Continue to whisk on a medium-high speed until stiff, thick and shiny.
As soon as you remove the cake from the oven, drop the oven temperature to 100C (210F). Open the oven door to help it cool down quicker if needed.
While the cake is still warm, place the cooling rack on top of the bundt pan and turn it upside down to release the cake. Remove the bundt pan and place the cooling rack on top of a baking tray.
Top the cake generously with the whipped meringue, then dust it with sprinkles. When the oven is at temperature, return the cake to the oven for 15 minutes to cook the meringue.
Remove the cake, then let it cool before serving.