Put the first base on a serving dish or on a cake stand.
Spread some buttercream on it and add some chocolate-chip.
Put another cake story, spread some buttercream on it and add other chocolate-chip.
Put the final story.
Fill a piping bag with the remainder buttercream and frost the cake completely. You can level the surface cake with a spatula.
With the aid of 3 or 4 wooden skewers, keep the cake so that it doesn’t lose its shape. Keep in the fridge for at least 1 hour.
Put the confetti sprinkles into a rectangular aluminium tin. Take back the cake from the fridge and roll it in the sprinkles.
You can choose to let the upper story frosted only with the buttermilk or covered entirely with the coloured sprinkles.
Keep the cake in the fridge until it’s time to serve it.
NOTE
There are two methods to prepare homemade buttermilk.
Mix together 250 ml of milk and 250 g of plain yogurt Add 30 ml of lemon juice to 250 ml of milk. Let it stand for 15 mins. at room temperature and then mix well
Personally, I prefer the latter :)
Recipe by OPSD Il gustoso food blog at https://www.opsd.it/torta-di-carnevale/