On a lightly floured surface with a lightly floured rolling pin, roll dough out to a circle about 14 inches in diameter; if the dough pulls back strongly, stop rolling, cover the dough with a kitchen towel and let rest 10 minutes before continuing.

Transfer dough to a round pizza pan, stone or large greased baking sheet; reshape dough as needed, but you can leave any edges of the dough hanging over the sides of the pan (they will be folded in later).

Cover with a towel and refrigerate.

Preheat the oven to 475°F and place a rack in the middle of the oven.

Cook bacon in a large skillet over medium heat until crisped, 8 to 10 minutes.

Transfer bacon to a paper-towel-covered plate to drain and when cool enough to handle, chop.

Pour off all but 1 tablespoon of grease left in skillet.

Return skillet to medium heat and add onion, garlic and salt.

Cook, stirring occasionally, until onion is golden and tender, about 15 minutes.

Add squash and cook, tossing gently once or twice, until any excess moisture evaporates, 2 to 3 minutes.

Scrape onion-squash mixture into middle of dough and spread evenly, leaving a 1-inch border around edges.

Sprinkle top with cheese and bacon.

Brush edge of dough with half the oil and fold it over to make a 1/2-inch rim.

Brush rim with remaining oil.

Bake until tart is deeply browned and dough is cooked through, 20 to 25 minutes.

Sprinkle with thyme and cool 10 minutes, then transfer to a cutting board and cut into wedges or squares for serving.