Instructions

• Preheat the oven to 170 °C (338 °F).
• Divide the sugar into two equal portions (40 g + 40 g). Measure out the other ingredients so they are ready: 400 ml milk, 1 egg (for the custard), 1/2 egg (for the wash), 25 g semolina, 12 g cornstarch, 5 ml vanilla extract, 25 g butter, zest of half a lemon, and 10 ml milk.
• In a medium pot, heat the 400 ml milk with one 40 g portion of the sugar over medium heat until it is hot and steamy but not boiling. Remove from heat.
• In a bowl, whisk together the 1 egg, the remaining 40 g sugar, 25 g semolina, 12 g cornstarch and 5 ml vanilla extract until smooth and lump-free.
• Temper the egg mixture: slowly pour about one-third of the hot milk into the egg mixture while whisking constantly, then continue adding the rest of the hot milk in a thin stream while whisking, until incorporated.
• Return the tempered mixture to the pot and place over low–medium heat. Whisk continuously and bring to a gentle boil; continue cooking and whisking for 1–2 minutes until the mixture thickens to a custard that coats the back of a spoon.
• While the custard is still hot, melt the 25 g butter. Reserve a small amount of the melted butter (a little on the spoon) to grease the pastry ring, then whisk the remainder into the custard off the heat. Stir in the zest of half a lemon. Set the custard aside to cool until warm or room temperature.
• When the custard has cooled to warm/room temperature, blend it briefly with an immersion blender or in a stand blender for a few seconds to produce a smooth, fine texture.
• Prepare a 14 cm (5½ in) steel pastry ring: line the bottom with aluminum foil, press a circle of baking paper over the foil on the bottom, and lightly brush the inside sides and bottom with the small amount of reserved melted butter to grease.
• Place the ring on a baking sheet (to catch any drips). Pour the blended custard into the prepared ring and smooth the surface with a spatula.
• Prepare the egg wash by beating the reserved 1/2 egg with 10 ml milk. Brush the egg wash evenly over the surface of the custard.
• Bake at 170 °C (338 °F) for 35–45 minutes, until the surface is set and lightly golden. Remove from the oven and let cool completely in the ring before unmolding and serving.