Birthday Cake with Chocolate Frosting

Step 1: Preheat the oven to 180°C/350°F (160°C fan) for 20 minutes before starting the batter. Position a rack in the middle of the oven.

Step 2: Grease three 20 cm / 8-inch cake pans with butter and line them with parchment paper. If possible, use pans without loose bases because the batter is quite thin.

Step 3: Whisk the flour, baking powder, and salt together in a large bowl. Set aside.

Step 4: Using a stand mixer fitted with a whisk attachment, or a hand beater, beat the eggs for 30 seconds on speed 6. Keep the beater running and pour in the sugar over 45 seconds, then beat on speed 8 for 7 minutes, until the eggs are white and have tripled in volume.

Step 5: While the eggs beat, put the butter and milk in a heatproof jug. Microwave on high for 2 minutes, until the milk is hot and the butter has melted, or heat them on the stove. Do not let the milk boil over.

Step 6: When the eggs are whipped, add the flour mixture in three batches, beating for 5 seconds on speed 1 between additions. Once all the flour is added, beat for another 5–10 seconds, just until no flour is visible, then stop immediately.

Step 7: Pour the hot milk, vanilla, and oil into the now-empty flour bowl. Add about 1 1/2 cups of cake batter to the hot milk mixture and whisk vigorously by hand until smooth and slightly foamy.

Step 8: Turn the beater back on at speed 1. Pour the milk mixture into the cake batter over 15 seconds, then turn off the beater.

Step 9: Scrape down the sides and bottom of the bowl. Beat on speed 1 for 10 seconds, until the batter is smooth and pourable.

Tip: Once you begin mixing the batter, continue through to putting it in the oven so the egg bubbles do not deflate.

Step 10: Divide the batter between the three pans, using 370 g / 13 oz per pan. Tap each pan on the counter three times to knock out large bubbles.

Step 11: Bake for 23 minutes, or until golden and a toothpick inserted into the center comes out clean.

Step 12: Remove the pans from the oven and leave the cakes in their pans for 15 minutes. Gently turn them out onto cooling racks and cool upside down; a slight dome will flatten as the cakes cool.

Step 13: Once the cakes are completely cool on the counter, refrigerate them for 30 minutes before frosting. Chilled cakes are firmer and easier to frost.

Step 14: Turn the cake layers upside down for flat surfaces. Spread 1 cup of chocolate frosting on each layer, then generously frost the sides and top. Use the remaining frosting to pipe decorative swirls on top.

Step 15: Decorate with sprinkles as desired. To add sprinkles around the base, place them around the bottom of the cake, scoop them up with a butter knife, and press them onto the sides.

Step 16: Heat the cream in a heatproof bowl until hot but not boiling. Add the cocoa powder and whisk until smooth and lump-free; the mixture will be a thin paste. Set aside for 5 minutes to bloom.

Step 17: Put the chocolate chips in a heatproof bowl and microwave in bursts until smooth: heat for 30 seconds on high, stir, then continue in 20-second increments.

Step 18: Add the cocoa paste to the melted chocolate and whisk until smooth. The mixture will be a thin paste. Leave it on the counter for 15 minutes to cool and thicken. If a skin forms, it will mix in during the next step.

Step 19: In a separate large bowl, beat the butter with a handheld mixer until soft and fluffy, about 1 1/2 minutes on high. Add the icing sugar and beat for about 30 seconds, until sandy and no large butter lumps remain. Add the cream cheese and beat for about 30 seconds, until smooth and creamy; stop when no yellow butter bits remain.

Step 20: Add all the chocolate paste and beat until combined.

Step 21: Cover the bowl with cling wrap and refrigerate for 2 hours, until thoroughly cold. The mixture can remain in the refrigerator at this point for days.

Step 22: Remove the bowl from the refrigerator. Add the 1/2 cup of cream and the salt, then beat on high for 1 1/2 minutes or until stiff peaks form. Use the frosting immediately.