These are a classic sweet treat from Canada. Like many classic desserts that seem to have dozens of "world's best" recipes, Butter Tarts seem to have dozens of "best" recipes. And the truth is, they're all "best" in one way or another. And this is one such classic Canadian Butter Tart recipe. You can use the pastry recipe below, or go the convenient route and use a prepared pastry crust from the market. The filling really is what makes it so great. Feel free to add raisins or nuts, if you like.
For the Pastry Dough: In a food processor, place the flour, salt, and sugar and process until combined. Add the butter and process until the mixture resembles coarse meal (about 15 seconds). Pour 1/8 cup water in a slow, steady stream, through the feed tube until the dough just holds together when pinched. If necessary, add more ice water.
Turn the dough onto your work surface and gather into a ball. Flatten into a disk, cover with plastic wrap, and refrigerate for about one hour before using. This will chill the butter and relax the gluten in the flour.
After the dough has chilled sufficiently, place on a lightly floured surface, roll out the dough and cut into 12 (4-inch) rounds. (To prevent the pastry from sticking to the counter and to ensure uniform thickness, keep lifting up and turning the pastry a quarter turn as you roll (always roll from the center of the pastry outwards).) Gently place the rounds into a 12-cup muffin tin. Cover and place in the refrigerator for about 30 minutes to firm the dough.
Preheat oven to 375°F (190°C).
For the filling: In the bowl of your electric mixer, or with a hand mixer, beat the butter and sugar until creamy and smooth. Beat in the eggs, one at a time, and then the vanilla extract. Stir in the cream.
If using nuts and/or raisins, place a spoonful in the bottom of each tart shell, and then fill the unbaked tart shells with the filling.
Bake at 375°F for about 15 to 20 minutes or until the pastry has nicely browned and the filling is puffed and set. Remove from oven and place on a wire rack to cool.
Run a knife around the inside edge of each muffin cup, to be loosen any pastry that might have stuck to the edge of the pan. Carefully lift each Butter Tart from the muffin cups, and place on a serving platter. Serve at room temperature or chilled.