3/4 stick (6 tablespoons):unsalted butter, cut into bits
2 cups pecans (1/2 lb),:toasted , cooled, and coarsely chopped
In a bowl whisk together the flour, baking powder, and salt and set it aside.
In a bowl of an electric mixer combine the butter and sugar and mix until pale and fluffy, about 3 minutes.
Beat in the egg and vanilla.
Reduce speed to low, then add flour mixture and mix until just combined.
Form a dough into a 12-inch log (2 inches in diameter) on a sheet of plastic wrap and roll up dough in plastic wrap.
Chill dough on a baking sheet until firm, at least 4 hours.
Line a 9X13 metal baking pan with foil and then grease it (leave a 2 inch overhang of foil on both ends.
then press dough evenly onto bottom of baking pan, using plastic wrap on top to prevent dough from sticking to your fingers, and chill until firm, about 20 minutes.
While crust chills, put oven rack in middle position and preheat oven to 375.
Bake crust until golden brown, about 30 minutes.
Cool in pan on a rack 20 minutes. (Leave oven on.) Make topping while crust cools:
Place the sugar in a heavy saucepan over moderate heat, and cook it, not stirring it until it begins to melt.
Continue to cook, stirring occasionally with a fork, until sugar is melted to a deep golden caramel.
Tilt the pan and carefully pour in the cream (the mixture will harden and steam vigorously, don't worry this is supposed to happen).
Cook over moderately low heat, stirring, until the cream is combined.
Remove the mixture from the heat and stir in butter, vanilla, salt, and pecans. Immediately spread the mixture over the cooled crust and return it to the oven and bake until bubbling, about 20 minutes.
completely in pan for several hours before cutting.
To cut, run a heavy knife under hot water, wipe dry and cut into triangles, diamonds, or squares.