In a large heavy bottom Dutch oven, heat butter over medium-high heat. Add sliced pears and cinnamon. Cook and stir for a couple of minutes. Stir in apple juice and brown sugar. Bring to a boil. Reduce heat to a simmer and cook and stir until thickened, about 7-9 minutes. Add a bit more apple juice if the sauce gets too thick. Remove from heat, stir in vanilla and allow to cool.
Preheat oven to 375°.
On a lightly floured surface, roll dough into a 14" circle. Transfer to a parchment paper-lined baking sheet.
Spoon pear filling over pastry. Spread filling out to within 2" of edge. Fold pastry edge over filling and squeeze together to make a pleat every two inches. Brush folded pastry with cream and sprinkle with coarse or sanding sugar. Bake until crust is golden and filling is bubbly, about 45-50 minutes. Allow to cool slightly before moving tart to a cooling rack. Move it with parchment in pace. Serve warm with vanilla ice cream or whipped cream.