Found this online...
I'm not sure if this is the one you're looking for, but the poster used the original filling and a different crust. Hopefully someone here will be able to find the full recipe for you. Meanwhile...
Caramelized Onion And Garlic Tart
This comes from a September 1993 issue of Bon Appetit. I replaced the crust recipe with one I got from my brother-in-law Sam Douglas, a professional chef, and have adapted it over time. The measurements for the pastry are by weight, so that the results are consistent. This is a very sexy tart.
CRUST
4½ ounces unbleached all-purpose flour
4½ ounces cake flour
4 ounces frozen unsalted butter, cut into cubes
2 ounces chilled solid vegetable shortening
3 ounces ice water
FILLING
2 tablespoons olive oil
2½ pounds onions, chopped
10 large garlic cloves, chopped
1 large fresh thyme sprig, or 1/4 teaspoon dried
1 bay leaf
½ cup dry white wine
1 cup packed shredded Gruyre cheese ( about 4 ounces )
For crust: Combine flour, butter and shortening in a food processor fitted with a steel blade and pulse the on/off switch until the mixture resembles coarse meal. Blend in the water one tablespoon at a time until the dough forms moist clumps. Gather the dough in a ball, flatten it into a disk, and wrap it in plastic. Refrigerate for 30 minutes. (Dough can be prepared 4 days ahead. Let it soften slightly before continuing.)
Preheat the oven to 400. Roll out dough on a floured surface (I use a pastry cloth) to a 12-inch round. Roll up dough on rolling pin, and transfer it to a 9-inch tart pan with a removable bottom. Press dough into pan and trim the edges. Poke some holes in the dough with a fork. Freeze for 15 minutes.
Line crust with foil and fill with beans or pie weights. Bake until set. Remove foil and weights. Continue baking until crust is golden brown, piercing with a fork if crust bubbles, about 15 minutes longer. Transfer to a rack, and cool completely.
For filling: Heat oil in a large heavy skillet over medium heat. Add onion, garlic, thyme and bay leaf and cook until onions brown and mixture is jam-like, stirring occasionally, about 50 minutes. Add wine; stir until all liquid evaporates, about 5 minutes. Season with salt and pepper. Cool. (Crust and filling can be made 6 hours ahead. Cover separately; let stand at room temperature.)
Preheat oven to 400. Remove thyme sprig and bay leaf from filling. Stir in the cheese. Transfer filling to crust. Bake until filling is brown, about 20 minutes. Remove pan sides from tart. Serve warm or at room temperature.
http://www.jimphotoglo.com/recipesSPR2000.htm
