In a medium bowl, whisk together the flour, Clabber Girl Baking Powder, and salt.
Using a pastry blender or your fingers, cut the butter into the flour until the mixture resembles coarse crumbs. Do not over mix (you should see pea size chunks of the butter).
Stirring with a fork, add the ice water and vinegar until the dough is moist enough to hold together when pinched between your thumb and forefinger. You may need more or less ice water to moisten the dough (you do not need to form the dough into a ball). Gather the dough, flatten into a disc, and wrap in plastic wrap. Refrigerate for at least one hour (or overnight).
When ready to bake, preheat the oven to 350 F.
Let the pastry dough sit at room temperature for about 15 minutes. If making tartlets, cut the dough into 6 equal pieces and press into circles to smooth out the edges (follow the instructions for each tartlet, rolling to the same thickness). On a very lightly floured surface, use a rolling pin to firmly and evenly kneed and roll the dough, turning frequently, to create a round disc about 10-inches in diameter. If the edges begin to crack, use one hand to pinch it back together and the other hand to press and flatten the dough. Finish shaping the dough with a firm rolling action, from the center out to the edges of the dough, to about 1/8-inch thickness, (pressing together any cracks that may form).
Roll the dough gently over the rolling pin and place over the tart pan, unrolling it into place. Press the dough firmly into the pan, especially in the corners. Trim the dough about 1/2-inch above the edge of the pan to allow room for shrinkage while baking. Prick holes evenly over the bottom of the pan, line with aluminum foil and fill crust with pie weights. Blind bake for about 12-15 minutes, remove foil, and continue baking for 5-10 more minutes or until lightly browned.
While the tart shells are baking, spread the pecans evenly on a baking sheet and place in the oven for about 8 minutes. Set aside to cool.
Whisk together the eggs, maple syrup, brown sugar, melted butter, and bourbon. Place the tart shell or shells on a baking sheet and arrange the pecans on the base of the pre-baked shell. Gently pour the maple and bourbon mixture over the pecans. Carefully return the baking sheet to the oven and bake for about 25 to 30 minutes (15 to 20 for the smaller shells) or until the tart is set in the center but still jiggles when you shake it.
Remove and allow tarts to cool for about 20 minutes before serving.
Yields One 9 to 10-inch Tart or Six 3-inch Individual Tartlets. Recipe by Mani Niall.