Preheat the oven to 375 degrees F. Make the crust: Pulse the flour, pecans, sugar and salt in a food processor until the pecans are finely ground. Pulse in the butter until the mixture resembles coarse meal. Add 2 tablespoons ice-cold water and pulse until the dough just comes together.
Turn out the dough onto a piece of plastic wrap, form into a disk, wrap and refrigerate until slightly firm, about 15 minutes. Put the dough in a 9-inch tart pan with a removable bottom and press into an even layer over the bottom and up the sides. Freeze until firm, about 10 minutes.
Place the tart pan on a baking sheet. Line the crust with foil and fill with pie weights or dried beans. Bake until the edges of the crust begin turning golden, about 20 minutes. Remove the foil and pie weights and continue baking until the crust is golden brown, 15 to 20 more minutes. Transfer to a rack and let cool completely.
Make the filling: Whisk 1 cup milk, the egg yolks, 1/4 cup sugar and the cornstarch in a medium bowl. Heat the remaining 2/3 cup milk and 1/4 cup sugar in a medium saucepan over medium heat and bring to a simmer. While whisking, slowly pour the hot milk mixture into the egg mixture. Return to the saucepan and cook, whisking constantly, until the mixture starts to bubble and is very thick, about 2 minutes. Remove from the heat, then whisk in the cream cheese, lemon juice and vanilla until smooth. Pour into the cooled crust and refrigerate until set, about 1 1/2 hours.
Make the topping: Toss the berries, sugar and sherry in a bowl and let sit at room temperature, 20 minutes. Top the tart with the berries.