We like the convenience of using ready-made pizza dough here; however, you can use our Cast-Iron Classic Pizza Dough .

Adjust oven rack to upper-middle position and heat oven to 500 degrees. Cook bacon in 12-inch cast-iron skillet over medium heat until crisp, 7 to 9 minutes. Using slotted spoon, transfer bacon to bowl. Measure out and reserve ¼ cup fat; discard remaining fat.

Add 2 tablespoons reserved fat, onions, thyme, sugar, and ¾ teaspoon salt to now-empty skillet. Cover and cook, stirring occasionally, until onions are softened, 8 to 10 minutes. Uncover and continue to cook, stirring occasionally, until onions are deep golden brown, about 10 minutes. Stir in vinegar and cook until almost completely evaporated, about 2 minutes; transfer to bowl.

Wipe skillet clean with paper towels, then grease with 1 tablespoon reserved fat. Place dough on lightly floured counter, divide in half, and cover with greased plastic wrap. Press and roll 1 piece of dough (keeping remaining dough covered) into 11-inch round. Transfer dough to prepared skillet and gently push it to corners of pan. Spread half of onion mixture over dough, leaving ½-inch border around edge. Scatter half of pear, half of crisp bacon, and ½ cup goat cheese evenly over top.

Set skillet over medium-high heat and cook until outside edge of dough is set, tart is lightly puffed, and bottom crust is spotty brown when gently lifted with spatula, 2 to 4 minutes. Transfer skillet to oven and bake until edge of tart is golden brown, 7 to 10 minutes.

Using potholders, remove skillet from oven and slide tart onto wire rack; let cool slightly. Being careful of hot skillet handle, repeat with remaining 1 tablespoon reserved fat, dough, and toppings. Sprinkle tarts with chives and cut into wedges. Serve.