1. Pate Sucree Extra: Pulse flour, sugar, and salt in a food processor to combine. Add butter and pulse just until mixture resembles coarse meal, about 10 seconds. In a liquid-measuring cup, whisk together ice water and egg yolks. With machine running, add egg-yolk mixture in a slow, steady stream just until dough holds together without being wet or sticky, about 30 seconds. To test, squeeze a small amount together; if it is crumbly, add more ice water, 1 tablespoon at a time. Turn dough out onto a piece of plastic wrap and divide in half. Shape each half into a disk, wrap tightly, and refrigerate until chilled, about 1 hour.

2. Divide one disk into 6 equal pieces (reserve remaining disk for another use). On a lightly floured surface, roll each piece into a ball and flatten into a 6-inch round with a rolling pin. Using your fingers, press rounds into bottom and up sides of six 4-inch round tart pans. Trim edges and refrigerate until firm, about 30 minutes.

3. Preheat oven to 350 degrees. Line each tart shell with parchment, pressing it into corners and edges, then fill with dried beans, rice, or pie weights. Place on a rimmed baking sheet and bake until sides are golden, 15 to 20 minutes. Remove parchment and beans. Continue baking until bottoms are cooked through and lightly golden, about 10 minutes more. Let cool completely.

4. Filling: Whisk together condensed milk and egg yolks until thoroughly combined. Whisk in lemon juice. Divide filling among tart shells. Bake until filling is set, 10 to 12 minutes. Transfer to a wire rack and let cool completely. Refrigerate until well chilled.

5. Italian Meringue: In a small saucepan over medium heat, bring sugar and 1/4 cup water to a boil. Continue boiling until a candy thermometer registers 238 to 240 degrees (soft-ball stage). Meanwhile, in the bowl of a mixer fitted with the whisk attachment, beat together egg whites, salt, and cream of tartar on medium-high speed until stiff (but not dry) peaks form (do not overbeat). Increase speed to high and add sugar syrup in a slow, steady stream, beating until mixture stops steaming, about 3 minutes.

6. Transfer meringue to a pastry bag fitted with a 1/2-inch round tip; pipe as desired. Using a small kitchen torch held at a 90-degree angle, move flame back and forth 3 inches from surface of meringue until it starts to brown (or broil 6 to 8 inches from heat source, about 1 minute). Serve immediately.