Prepare the pudding: whisk cornstarch, egg yolks, and a splash of milk until smooth. Heat the remaining milk with sugar and cinnamon over medium heat until just before boiling, then stir in the cornstarch mixture and cook until thickened, around 5 minutes. Transfer to a bowl, cover with plastic wrap, and refrigerate overnight.

Make the cupcake batter: Preheat oven to 175°C (350°F) and line muffin tin. Cream softened butter, sugar, and a pinch of salt until fluffy, about 3–5 minutes. Add vanilla extract and room temperature eggs one at a time, mixing well. Fold in flour and baking powder, followed by a pinch of cinnamon and fill liners two-thirds full.

Bake the cupcakes: Place the filled muffin tin in the preheated oven and bake for 15–20 minutes, or until a toothpick comes out clean. Allow cooling in the tin for 5 minutes before transferring to a wire rack.

Prepare the topping: Once pudding is chilled, whip it until fluffy. Combine mascarpone and cream cheese, then gently fold in the whipped pudding until smooth. Keep refrigerated until ready to use.

Decorate the cupcakes: Once cooled, pipe the creamy mascarpone topping onto each cupcake, sprinkle with cinnamon sugar, and top with Cini Minis.