A butter tart is a type of small pastry tart highly regarded in Canadian cuisine. My mother, Dorothy, made this recipe her entire life, it was passed to her by her mother, so we have approximately 160 years of this luscious, gooey dessert in my bloodline. It's relatively simple but as simple as it is it's one of the best desserts I've ever had. The buttery flaky crust, the gooey filling, the moist raisins all work to produce a dessert fit for a king. Close your eyes as you take the first bite and savor it all - I promise you on my mother's apron you will fall in love with these tarts.
PASTRY: In large bowl, whisk flour with salt. With pastry blender or 2 knives, cut in butter and lard until mixture resembles coarse crumbs with a few larger pieces.
In liquid measure, whisk egg yolk with vinegar; add enough ice water to make 1/3 cup. Sprinkle over flour mixture, stirring briskly with fork until pastry holds together. Press into disc; wrap in plastic wrap and refrigerate until chilled, about 1 hour. Make-ahead: Best if refrigerated for up to 3 days.
Preheat oven to 350˚F.
FILLING: In a large bowl beat the eggs well. Add sugar, maple syrup, and melted butter and beat again, then add the raisins, currants, vinegar, salt, and vanilla extract and mix vigorously.
Roll out dough to 1/4"-inch thickness on a floured board, use a 3"-inch pastry cutter to cut out circles of dough. Spray nonstick baking spray into tart tins or muffin pans, then place circles of dough in the pans working the dough with you fingers to it reaches to top of the pans.
Fill the pastry shells 2/3 full with the sugar-maple syrup-raisin mixture and bake until the pastry is light brown, about 20 minutes.
Hire an armed guard to help you distribute the tarts - believe me you'll need one after people get their first taste.