1/2 cup (1 stick) unsalted butter, room temperature
1/2 cup plus 2 tablespoons
1 large egg yolk
3 1/2 ounces high-quality milk chocolate (such as
Lindt or Perugina), chopped
2 cups heavy whipping cream, divided
(1/2 stick) unsalted butter
1/2 cup plus 2 tablespoons sugar
Unsweetened cocoa powder (for dusting)
Make crust. Whisk flour and cocoa in medium bowl.
Beat butter and confectioners' sugar in another medium bowl until well blended.
Beat in yolk.
Add flour mixture in 2 additions, beating just until blended.
dough into ball; flatten into disk. Wrap in plastic and refrigerate 2 hours.
Divide dough into 6 equal pieces. Press each onto bottom and up sides of 4 1/2-inch
diameter tartlet pan with removable bottom.
Refrigerate crusts for 1 hour or freeze
for 30 minutes.
Heat oven to 375 degrees F.
Bake cold crusts until set and dry-looking, about 12 minutes, pressing with back
of spoon if bubbles form. Cool crusts in pans.
Make filling. Place milk chocolate in medium bowl. Bring 1 1/2 cups cream to
simmer in small saucepan. Pour hot cream over chocolate; let stand 1 minute, then
whisk until melted and smooth. Cover with plastic wrap and refrigerate until cold,
for at least 4 hours or overnight.
Combine remaining 1/2 cup cream and butter in small saucepan and stir over medium
heat until butter melts; remove from heat.
Combine sugar and 3 tablespoons water
in heavy small saucepan. Stir over medium-low heat until sugar dissolves. Increase
heat and boil without stirring until color is deep amber, occasionally brushing
down sides of pan with wet pastry brush and swirling pan, about 8 minutes.
add hot cream-butter mixture (mixture will bubble vigorously). Remove from heat
and stir until any caramel bits dissolve.
Transfer caramel to small bowl and chill
until slightly firm (semi-soft), stirring often, about 40 minutes.
Spoon caramel into center of baked crusts (about 2 generous tablespoons for each
crust). Set aside.
Using electric mixer, beat chilled milk chocolate-cream mixture until peaks form;
spoon atop caramel in crusts, dividing equally (about 1/2 cup for each crust) and
Chill at least 2 hours.
Remove tartlets from pans.
Lightly sift cocoa powder over tartlets and serve.
Makes 6 servings.
Do ahead: Can be made 8 hours ahead. Cover
and keep refrigerated.