Candied Orange Slices
3 to 4 medium-size, juicy oranges
    (preferably seedless)
3 tablespoons corn syrup
1 1/4 cups granulated sugar

With a large, sharp serrated knife, slice oranges crosswise into scant 1/8-inch thick slices, discarding smaller end pieces or imperfect slices. Combine corn syrup, 1/2 cup hot tap water and sugar in a 12-inch skillet over medium heat, stirring until well blended. Bring mixture to a simmer. Lay orange slices in pan. Adjust heat so mixture simmers gently and cook, uncovered, for 20 - 30 minutes, or until slices are translucent and tender. Using a slotted spoon, gently lay slices, slightly separated, on a large sheet of wax paper. If necessary, boil down cooking syrup until just slightly thickened. Reserve syrup for garnishing tart top.

Pastry
1 1/4 cups all-purpose flour
2 1/2 tablespoons granulated sugar
1/4 teaspoon salt
6 1/2 tablespoons cold unsalted butter, cut into 1/2-inch pieces

Set out a 10 x 1-inch tart pan with removable bottom.

In a food processor fitted with a steel blade, combine flour, sugar and salt. Process a few seconds to blend. Sprinkle butter over flour mixture. Process in on/off pulses until butter is cut into flour and mixture resembles coarse meal. Processing with on/off pulses, add 1 tablespoon cold water through feed tube, processing only until liquid is evenly incorporated and particles begin to hold together. If mixture is crumbly, continue sprinkling water, a teaspoon at a time, and processing with on/off pulses, until mixture holds together smoothly, being careful not to over-process or over-moisten. Press pastry into a ball.

Alternatively, if processor is unavailable, in a medium bowl, using pastry blender, forks, or your fingertips, cut butter into flour mixture, until mixture resembles coarse meal. Add 1 tablespoon cold water to flour mixture, blending with a fork, just until particles hold together. If necessary, add a little more cold water, a teaspoon at a time, to moisten pastry enough to hold together well. Knead lightly to form pastry into a ball.

Place pastry between two sheets of wax paper and roll into an even 12-inch round, checking underside of dough frequently and smoothing out any wrinkles that form. Refrigerate dough on a large tray or baking sheet for 25 to 30 minutes.

Let dough soften at room temperature for several minutes. Peel off one sheet of paper. Turn dough over and drape, centered, in pie plate. Fit pastry into place, smoothing over bottom and sides and patching any breaks or tears. Trim off dough at pan rim. Prick pastry all over using a fork. Grease a sheet of heavy-duty aluminum foil and press, greased side down, into pastry shell; fold out over pan edges to completely cover pastry. Refrigerate at least 30 minutes and up to 8 hours, if desired.

Partially bake shell by preheating oven to 400 degrees F and baking with foil in place for 12 minutes. Gently remove foil and bake 5 minutes longer. Set aside on wire rack. Reset oven to 375 degrees F.

Filling
1/4 cup unsalted butter, cut into chunks
4 ounces bittersweet (not unsweetened) or semisweet
    chocolate, coarsely broken or chopped
1 tablespoon all-purpose flour
3 tablespoons heavy (whipping) cream
2 large eggs
3 1/2 tablespoons clover honey
1 1/4 teaspoons vanilla extract
Finely grated zest (orange part of skin) of
    1 large orange
3/4 cup (about 3 1/2 ounces) finely chopped, toasted
    and hulled hazelnuts (or finely chopped walnuts,
    if preferred - see note)

Combine butter and chocolate in a small, heavy saucepan on lowest heat, stirring until melted and smooth. Set aside.

In a medium bowl, beat together flour and cream until well blended. Using a fork, beat in eggs, then honey, vanilla extract and orange zest. Add chocolate mixture and toasted hazelnuts and continue beating with a fork until evenly incorporated.

Pour mixture into prepared tart shell. Set tart pan on baking sheet. Bake on center oven rack for 22 to 27 minutes, until mixture is slightly puffed and set when tapped on top. Transfer to wire rack. Brush a little reserved orange cooking syrup over tart surface (if it is too stiff to work with, warm it slightly first). Select the prettiest, most perfect candied orange slices (reserve remainder for another use or discard), and arrange, overlapping as desired over tart surface. Drizzle slices with several tablespoons of orange cooking syrup. Refrigerate tart until thoroughly cooled, at least 1 1/2 hours, before serving.

Store, refrigerated, up to 5 days. Serve at room temperature or slightly chilled. Cut into wedges with a very sharp knife.

NOTE: To prepare hazelnuts, toast in a preheated 350 degree F oven for 12 to 15 minutes, until nuts brown and hulls loosen. Rub cooled nuts in kitchen towel or between your fingers, discarding loose bits of hull. Chop nuts finely.