Preheat oven to 425°.
Roll dough into a 10-inch circle on a lightly floured surface; set aside.
Combine brown sugar and the next 4 ingredients (brown sugar through plums). Combine the granulated sugar and lemon juice in a 10-inch cast iron skillet, and cook the mixture over medium-high heat just until it begins to turn golden.
Remove from heat; stir until completely golden. Add pecans and plum mixture. Place dough over plum mixture, tucking dough around plums.
Bake at 425° for 25 minutes or until bubbly. Immediately place a plate over pan. Carefully invert tart onto plate.