Using a rolling pin, roll dough into a large circle. Cut four circles with a 6-inch round cookie cutter (or trace the bottom of a small plate). Transfer to four 4-inch mini tart pans with removable bottoms. Trim excess dough, then freeze the tart shells for 20 minutes.
Remove the tart shells from the freezer and prick the bottom of eachwith a fork. Cover with a sheet of aluminum foil, pressing snugly up against the sides of the pan.
Place the tart pans on a half sheet baking pan lined with a Silpat silicone mat or parchment paper (to match drips). Blind bake the tart shells until the crust is just set, about 15 minutes. Remove the foil and bake until the shells are light brown, about 5 minutes more.
Meanwhile, heat syrup in a small saucepan over medium heat until it’s warm and loose. Remove pan from heat and stir in the bread crumbs, heavy cream, egg, butter, zest, and salt. Set the filling aside.
Remove the tart shells from the oven. Pour the filling into each tart shells about ¾ full.
Bake until the filling is just set, about 15 to 20 minutes. Cover the tarts with foil if the crusts are getting too brown.
Remove the pan from oven, and transfer tarts to wire rack to cool.
Serve with lightly sweetened whipped cream.
When making the short crust pastry, measure 1 egg into a small bowl. Use 1/2 for making the pastry and the other 1/2 to make the tart filling.Use fresh bread crumbs made from white or egg bread. Avoid wheat bread as it can impart a bitter taste to the filling.One 4-inch tart serves two in our family. The rest freeze well. Defrost overnight in the refrigerator to thaw.For one full-sized tart, double the recipe and use a 9-inch tart pan with a removable bottom. Increase the short crust blind baking to a total of 30 minutes, and bake the filling for 30 minutes or until set.