To make the pistachio paste: Bring a small saucepan of water to a boil. Add the shelled pistachios and simmer 2 minutes. Drain andrinse the nuts under cold water to cool them completely. Dry the nuts with paper towels when put them in a large measuring cup. Add the sugar and milk and use a hand blender to process the mixture to a super smooth consistency. (You can also do this in a food processor, but the texture of the pistachio paste may not become as smooth as if you used a hand blender. This will in no way prevent the dessert from being totally delicious!)
To make the pistachio cream: Pour the milk in a medium saucepan, add the pistachio paste, and heat until the mixture simmers—don’t bring it to a full boil. While the milk mixture is heating up, whisk the egg yolks, sugar, cornstarch, and salt together in a mixing bowl. The mixture will be thick but make sure to whisk until it’s smooth.
When the milk and pistachio mixture simmers, remove it from the heat. Ladle about ½ cup (125 ml) hot milk and pistachio mixture and slowly pour it into the egg mixture while whisking. This will ensure the eggs heat up gradually and don’t cook and turn grainy. Whisk in another ladleful of hot milk into the egg mixture. Pour the egg mixture back into the saucepan containing the rest of the hot milk mixture, whisking constantly while you pour. Put the saucepan back over low heat and cook, whisking constantly, until the cream thickens to a pudding consistency, about 3 minutes. Remove from the heat.
Divide the pistachio pudding between 6 small glasses or ramekins. Each glass should be filled up to a generous third to leave room for the strawberries and pistachio crumble toppings. Cover with plastic wrap and refrigerate until the cream is completely cool, about 2 hours.
To make the pistachio crumble: Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper. In a large bowl, whisk the flour, sugar, and pistachios together. Add the cold butter and incorporate it to the dry ingredients using a pastry cutter, a fork, or your hands, until the mixture turns to sticky pea-sized crumbs. Spread the mixture over the prepared baking sheet and bake for 10 minutes until the crumbs are golden (mixing the crumbs halfway through baking allows them to brown more evenly). Let cool completely.
To make the macerated strawberries: Up to an hour before serving the pistachio puddings, in a nonreactive mixing bowl, combine the vanilla seeds, paste, or extract with the sugar. Quarter or dice the strawberries (depending on their size) and add them to the bowl. Gently toss to coat the strawberries with the vanilla sugar and leave to macerate at room temperature until ready to serve. It’s best to macerate the strawberries for a minimum of 15 minutes, and up to a maximum of 60 minutes.The longer the strawberries macerate, the softer and mushier they will become, and in this recipe, it’s best if the strawberries remain firm and juicy.
SERVING: Bring the puddings back to room temperature 15 to 60 minutes before serving. Divide the macerated strawberries between each serving. Generously sprinkle with pistachio crumbs. Serve right away!
STORAGE: The pistachio puddings will keep, refrigerated, for up to 5 days. Always make sure to add the macerated strawberries and pistachio crumbs right before serving.
NOTE: Pistachios sold in their shells must be, of course, shelled, but also peeled before being used to make pistachio cream because the brownish skin that covers the nuts would alter both the color and texture of the cream. To peel the pistachios, simmer, rinse and dry as described in the recipe, then remove the skin by pinching each nut each between your fingers. You be left with gorgeous, bright green pistachio nuts. Use them as indicated in the recipe. (Discard the skins.)
MAKE IT DAIRY-FREE: Substitute unsweetened oat milk or almond milk in both the pistachio paste and pistachio cream. Use vegan butter or magarine in the pistachio crumble.