Step 1: Preheat your oven to 400°F (200°C). Prick the sweet potatoes with a fork and roast them on a baking sheet for 45-60 minutes until very soft.
Step 2: While potatoes roast, blind bake your tart shell by lining it with parchment paper and pie weights. Bake at 375°F for 15 minutes, then remove weights and bake for 5 more minutes. Set aside to cool.
Step 3: Once the sweet potatoes are cool enough to handle, peel away the skins and mash the flesh. Pass the mash through a fine-mesh sieve to ensure a smooth texture for the sweet potato pecan tart.
Step 4: In a large bowl, whisk together the sweet potato purée, brown sugar, maple syrup, eggs, heavy cream, vanilla, and spices until fully combined and smooth.
Step 5: Reduce oven temperature to 350°F (175°C). Pour the sweet potato filling into the pre-baked tart shell, smoothing the top with a spatula.
Step 6: Toss the pecan halves with melted butter and a pinch of salt. Arrange them in decorative concentric circles on top of the filling.
Step 7: Bake the sweet potato pecan tart for 35-40 minutes, or until the filling is set but still has a slight jiggle in the center.
Step 8: Allow the tart to cool completely on a wire rack for at least 2 hours before slicing. This ensures the custard sets properly.