Preparation Position rack in top third of oven; preheat to 450°F. Heat wine and butter in heavy medium skillet over medium-low heat until butter melts. Add leeks. Cover; cook until leeks are crisp-tender, about 4 minutes. Remove from heat. Mix in marjoram. Reserve 2 teaspoons egg; stir remaining egg into leek mixture. Meanwhile, unroll pizza dough on lightly floured baking sheet. Stretch or pull dough to 13 x 10-inch rectangle. Spread leek mixture over dough, leaving 1-inch border on all sides. Sprinkle cheese and pepper over filling. Fold 1-inch border in over filling. Brush folded edge with reserved 2 teaspoons egg. Bake galette until crust is golden brown, about 14 minutes. Cut galette into 4 pieces and serve warm.
Preparation Position rack in top third of oven; preheat to 450°F. Heat wine and butter in heavy medium skillet over medium-low heat until butter melts. Add leeks. Cover; cook until leeks are crisp-tender, about 4 minutes. Remove from heat. Mix in marjoram. Reserve 2 teaspoons egg; stir remaining egg into leek mixture. Meanwhile, unroll pizza dough on lightly floured baking sheet. Stretch or pull dough to 13 x 10-inch rectangle. Spread leek mixture over dough, leaving 1-inch border on all sides. Sprinkle cheese and pepper over filling. Fold 1-inch border in over filling. Brush folded edge with reserved 2 teaspoons egg. Bake galette until crust is golden brown, about 14 minutes. Cut galette into 4 pieces and serve warm.