1. Preheat the oven to 320°F for a fan-forced oven or 350°F for a conventional oven. Line a 15 x 12 x 2-inch rectangular baking pan with parchment paper.

2. Heat the milk and butter in a saucepan until the butter melts. Stir in the salt. Do not boil the mixture. Set it aside while you sift the cake flour and baking powder into a bowl.

3. Beat the sugar, eggs, and vanilla bean paste on medium-high speed for 5 minutes until thick, pale, and fluffy.

4. Add the warm milk mixture and whisk for about 15 seconds. Add the flour mixture in two batches and mix on low speed just until smooth. Do not overmix.

5. Pour the thin batter into the prepared pan. Bake for 30 to 35 minutes, or until the center springs back when lightly pressed.

6. Cover the pan with a baking dish or clean tray while the cake cools. This traps steam and helps the sponge stay moist.

7. Make the buttercream while the cake cools. Beat the softened butter on medium-high speed for 2 minutes until pale and creamy.

8. Add the sifted icing sugar in four batches while mixing on low speed. Add the milk and vanilla bean paste, then beat on medium-high speed for 3 minutes until fluffy. Transfer the frosting to piping bags.

9. Cut 20 cake rounds with a 2.8-inch round cutter. Keep the cuts close together to reduce waste.

10. Place one cake round inside each ice cream cup. Brush or drizzle it with simple syrup, if using. Pipe buttercream around the edge and across the center.

11. Add a second cake round. Brush it with simple syrup, then pipe buttercream around the edge and across the top. Smooth the frosting with an angled spatula.

12. Pour the sprinkles into a wide bowl. Carefully dip the frosted top of each Mini Dot Cake into the sprinkles until evenly coated.

13. Serve immediately, or store the finished cakes in an airtight container until needed.