Step 1: In a large mixing bowl, combine the all-purpose flour and salt. Add the cold, cubed salted butter and work it into the flour until it resembles coarse crumbs.
Step 2: Add very cold water a tablespoon at a time, mixing gently until the dough comes together. Gather into a ball, flatten into a disc, wrap in plastic wrap, and refrigerate for at least 30 minutes.
Step 3: Roll out the chilled dough on a floured surface to about 1/8 inch thick. Cut out circles and place them into tart pans, trimming excess dough.
Step 4: In a medium bowl, mix together brown sugar, maple syrup (or corn syrup), eggs, and vanilla extract until smooth.
Step 5: Preheat oven to 375°F (190°C). Fill each tart shell with the prepared filling, leaving space at the top.
Step 6: Bake for 25-30 minutes until the filling is bubbly and the pastry edges are golden brown. Rotate pans halfway through baking.
Step 7: Allow the tarts to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely. Enjoy warm or at room temperature.
Notes
For best results, use cold ingredients and do not skip the chilling step. You can customize the filling with nuts or chocolate if desired.