Whirl flour with 2 tbsp granulated sugar and 1/2 tsp salt in a food processor. Add 1 cup butter. Pulse until crumbs form. With motor running, add ice water and juice through spout. Continue whirling just until dough comes together. It should not be sticky. Divide into 8 portions and form each into a disc. Wrap with plastic wrap and refrigerate until chilled, at least 30 min or overnight. Position a rack in lower third of oven. Preheat to 425F. Combine brown sugar with cornstarch and 1/8 tsp salt in a large bowl. Stir in plums and ginger until evenly coated. Distribute fruit mixture among 8 small baking dishes. Top each with a few cubes of butter. Place dishes on a large baking sheet. On a floured surface, roll 1 pastry disc into a circle to just cover top of a baking dish. Loosely roll up around rolling pin. Then unroll over dish and trim if needed. Crust should be even with the edge of baking dish, but not overhanging. Cut 4 small slits in pastry. Repeat with remaining discs. Lightly brush tops of pastry with cream. Don’t let it pool. Sprinkle with remaining 1 tbsp sugar. Bake in lower third of oven until crust is golden and plums are tender, 35 to 45 min. Serve with ice cream. Time-Saving Variation: Use a 9 × 13-in. baking dish instead of individual baking dishes. No need to divide pastry into portions! Shape into a large rectangle and refrigerate at least 1 1/2 hours or overnight. Roll pastry into a rectangle about 9 × 13 in. Continue with recipe.