Preheat oven to 425°F. Set a foil-lined baking sheet on the lower rack.
Toss berries with sugar, cornstarch, lemon juice, zest, vanilla, cinnamon, and salt.
Let the filling rest 10 minutes to start juicing.
Dust the counter with flour. Roll one dough round to a 12-inch circle.
Fit dough into a 9-inch pie plate. Chill while you prepare the top.
Spoon filling into the shell. Mound slightly. Dot with the butter pieces.
Roll the second dough. Top the pie. Lattice or leave whole; seal and crimp edges.
Cut a few vents if using a solid lid.
Brush with cream. Sprinkle the top with coarse sugar.
Bake 20 minutes. Reduce to 375°F; bake 30–35 minutes until bubbling and deeply golden.
Cool at least 3 hours before slicing for clean pieces.