Boston Cream Pie Cookies

In a saucepan, heat the milk over medium heat until warm but not boiling. In a separate bowl, whisk sugar, egg yolks, and cornstarch until smooth. Slowly pour the warm milk into the egg mixture while whisking constantly. Return everything to the saucepan and cook over medium-low heat, stirring continuously until thick and smooth. Remove from heat, stir in butter and vanilla essence, then transfer to a bowl. Cover with plastic wrap directly touching the surface and chill for at least 30 minutes.

Cream the softened butter and sugar together until light and fluffy. Add the egg and vanilla essence, mixing until fully incorporated. In another bowl, combine flour, baking powder, and salt. Gradually mix the dry ingredients into the wet ingredients until a soft dough forms. Chill the dough for 30 minutes to prevent spreading.

Preheat the oven to 175°C. Line baking trays with parchment paper. Scoop tablespoon-sized portions of dough and roll into balls. Place them on the tray, spacing evenly. Bake for 12–14 minutes until the edges are lightly golden. Allow cookies to cool completely on a wire rack.

Pipe or spoon a generous amount of chilled custard onto the flat side of half the cookies. Top with the remaining cookies to form sandwich cookies. Gently press to spread the filling evenly.

Heat the cream until just simmering. Pour it over chopped chocolate and butter in a heatproof bowl. Let sit for 2 minutes, then stir until smooth and glossy.

Spoon or drizzle chocolate glaze over the tops of the assembled cookies. Let them set at room temperature or refrigerate for 15 minutes until the glaze firms up.