Pastry: 2 1/3 cups all-purpose flour 4 tsp granulated sugar 1 tsp salt 1 cup cool unsalted butter 1 large egg 2 tbsp cold water
Filing: 3/4 cup packed dark brown sugar 3/4 cup corn syrup or maple syrup 1/2 cup unsalted butter, melted 2 large eggs, room temperature 1 tsp white vinegar 1 tsp vanilla extract OR the seeds from 1/2 a vanilla bean 1/2 cup golden raisins
Method
1. In a mixer fitted with a paddle attachment, combine flour, sugar and salt. Cut the cold butter into small pieces (pull butter from the fridge 30 minutes before adding) and add to the flour, mix until dough is a rough, crumbly texture. Add egg and water at once and whisk, mixing until dough forms. Shape the dough into 2 logs, wrap in plastic and chill for at least one hour.
2. Preheat the oven to 400°F (200°C) and lightly grease a 12-cup muffin tin with butter. Lightly dust a work surface with flour and unwrap pastry logs. Slice each log into six equal pieces. Roll each piece to about 1/4-inch thickness and line each muffin cup (you can trim the crust, or leave the "ruffle" of pastry for a pretty effect once it bakes). Chill lined muffin tin while preparing filling.
3. Whisk sugar, corn syrup and butter in a bowl by hand until combined. Whisk in the eggs, then add the vinegar and vanilla or vanilla bean seeds. Sprinkle a few raisins in the bottom of each muffin cup and pour the filling over the raisins.
4. Bake the tarts for 5 minutes, then reduce heat to 375°F (190°C). Continue baking until butter tart filling starts to rise and form a dome after about 20 more minutes. Remove from the oven and allow tarts to cool before removing them from the tin.