Prepare the Crust: In a food processor, combine all-purpose flour, sugar, and salt, pulsing until mixed. Cut in cold unsalted butter until the mixture resembles sandy crumbs. Gradually add cold water, one tablespoon at a time, until the dough just holds together. Shape into a disc, wrap in plastic, and chill in the refrigerator for 30 minutes to firm up.

Roll Out the Crust: On a lightly floured surface, roll the chilled dough into a 12-inch circle, about 1/8-inch thick. Carefully place the rolled dough into a tart pan, trimming any excess from the edges. Freeze the crust for 10 minutes to set. Preheat your oven to 375°F (190°C) while you prepare the next steps.

Blind Bake the Crust: Once the oven is heated, line the tart crust with parchment paper and fill it with ceramic pie weights or dried beans. Bake for 15-18 minutes, or until the edges are golden brown. Remove the weights and parchment, then return the crust to the oven for an additional 5 minutes until the base is lightly browned and dry.

Make Chai Custard: In a medium saucepan, heat whole milk, heavy cream, and black tea bags over medium heat until it just begins to simmer. Allow the mixture to steep for 10 minutes to infuse the chai flavor. Remove the tea bags and whisk the egg yolks, sugar, cornstarch, vanilla extract, and chai spice in a bowl until smooth and well-combined.

Temper the Egg Mixture: Gradually whisk about a cup of the warm milk mixture into the egg yolk mixture to temper it, avoiding curdling. Return the entire mixture to the saucepan over low heat, stirring continuously for about 4 minutes until the custard thickens and is smooth. Remove from heat and let it cool for 10 minutes.

Assemble with Pears: Thinly slice your ripe pears and artfully arrange them on top of the cooled custard in the tart crust, forming concentric circles. Once arranged, bake the Chai-Spiced Pear Tart at 350°F (175°C) for 20-25 minutes, or until the custard jiggles slightly but is set in the center, creating a luscious filling.

Cool and Serve: Allow the tart to cool at room temperature for at least 1 hour before slicing. For an elegant touch, dust with powdered sugar before serving. Pair with a drizzle of honey or a dollop of whipped cream if desired.