Make the raspberry puree: Add raspberries, 1/4 cup sugar, and lemon juice to a small saucepan over medium heat. Cook for 5–7 minutes, stirring often, until the berries break down and release their juices. Use a spoon to mash them gently.

Strain the seeds: Press the cooked berries through a fine-mesh sieve into a bowl to remove seeds. Scrape the underside of the sieve to catch every bit of puree. You should have about 1 to 1 1/4 cups of smooth raspberry puree.

Warm the milk: In a medium saucepan, combine milk and cream (if using) with a pinch of salt. Heat over medium-low until steaming but not boiling. Turn off the heat and set aside.

Whisk the base: In a separate bowl, whisk the remaining 1/4 cup sugar with cornstarch and egg yolks until thick and smooth. This should look pale and glossy. If it feels too thick, add a splash of the warm milk to loosen it.

Temper the eggs: Slowly pour in about 1/2 cup of the warm milk mixture into the yolk mixture while whisking constantly. This prevents curdling. Then pour the tempered mixture back into the saucepan with the rest of the milk.

Cook the pudding: Return the pan to medium heat and whisk continuously for 4–6 minutes until the mixture thickens. Look for steady bubbles and a texture that coats the back of a spoon. Don’t walk away—constant whisking keeps it silky.

Add the raspberry puree: Remove the pan from heat. Stir in the raspberry puree, vanilla, and lemon zest. Taste and add 1–2 extra tablespoons of sugar if you prefer it sweeter.

Finish with butter (optional): Whisk in the butter for extra shine and richness. This step helps create a smoother finish.

Strain again (recommended): For the smoothest texture, pour the pudding through a clean fine-mesh sieve into a large bowl or a jug. This catches any tiny bits of egg or fruit.

Chill or serve: Pour into serving cups or a large dish. If chilling, press plastic wrap directly onto the surface to prevent a skin. Refrigerate for at least 2 hours for a set, spoonable texture. Or serve warm for a cozier feel.

Garnish: Top with a dollop of whipped cream, fresh raspberries, or a sprinkle of crushed shortbread for crunch. A few mint leaves add a fresh look.