Whisk flour, sugar, and 1 teaspooncoarse salt in large bowl to blend.
Addbutter and rub in with fingertips untilcoarse meal forms. Stir cream and eggyolk in small bowl until blended; drizzleover flour mixture. Stir until dough comestogether in moist clumps. Gather doughinto ball; flatten into disk. Wrap and chillat least 1 hour and up to 1 day.
Roll out dough on floured surface to12-inch round.
Transfer to 9-inch tart panwith removable bottom.
Cut off all but1/2-inch overhang. Fold overhang in andpress, forming double-thick sides. Piercebottom of crust with fork; chill 30 minutes.
Preheat oven to 350°F. Line crust withfoil and fill with dried beans or pie weights.
Bake until sides of crust are set, about20 minutes.
Remove foil with beans andbake until crust is golden brown, 12 to 15minutes longer. Cool crust completely.
Combine bittersweetchocolate and carob in medium bowl.Bring cream to simmer in heavy mediumsaucepan over medium heat.
Pour creamover chips; let stand 1 minute. Stir untilmelted and smooth.
Add butter and vanilla;stir to blend.
Pour filling into cooled crust.Chill uncovered until firm, at least 4 hours.Chop brittle into rough 1/2-inch pieces.DO AHEAD: Can be made 1 day ahead. Coverbrittle, cover tart, and keep chilled. Bring toroom temperature before continuing.
Remove tart from pan. Scatter brittleover tart and serve.
* Carob chips are similar to chocolatechips. They are available at somesupermarkets and at specialty foods storesand natural foods stores.