Fresh Tomato Galette

Instructions

Cook along with these step-by-step instructions

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Process flour and ½ teaspoon salt in food processor until combined, about 3 seconds. Scatter butter over top and pulse until mixture resembles coarse crumbs, about 10 pulses. Transfer to large bowl. Sprinkle 6 tablespoons ice water over flour mixture. Using rubber spatula, stir and press dough until it sticks together, adding up to 1 tablespoon more ice water if dough doesn't come together.
Turn out dough onto lightly floured counter, form into 4-inch disk, wrap tightly in plastic wrap, and refrigerate for 1 hour. (Wrapped dough can be refrigerated for up to 2 days or frozen for up to 1 month.)
Toss tomatoes and 1 teaspoon salt together in second large bowl. Transfer tomatoes to colander and set colander in sink. Let tomatoes drain for 30 minutes.
Recipe Tip
Shaking the colander well after a 30-minute rest helped ensure that no added liquid entered the crust.
Adjust oven rack to lower-middle position and heat oven to 375 degrees. Line rimmed baking sheet with parchment paper. Let chilled dough sit on counter to soften slightly, about 10 minutes, before rolling. Roll dough into 12-inch circle on lightly floured counter, then transfer to prepared sheet.
Recipe Tip
Dough may run up lip of sheet slightly; this is OK.
Shake colander well to rid tomatoes of excess juice. Combine tomatoes, shallot, oil, thyme, garlic, pepper, and remaining ½ teaspoon salt in now-empty bowl. Spread mustard over dough, leaving 1½-inch border. Sprinkle Gruyère in even layer over mustard. Shingle tomatoes and shallot on top of Gruyère in concentric circles, keeping within 1½-inch border. Sprinkle Parmesan over tomato mixture.
Recipe Tip
Sharp cheddar cheese can be used in place of the Gruyère, if desired.
Carefully grasp 1 edge of dough and fold up about 1 inch over filling. Repeat around circumference of tart, overlapping dough every 2 inches, gently pinching pleated dough to secure. Brush folded dough with egg (you won't need it all).
Bake until crust is golden brown and tomatoes are bubbling, 45 to 50 minutes. Transfer sheet to wire rack and let galette cool for 10 minutes. Using metal spatula, loosen galette from parchment and carefully slide onto wire rack; let cool until just warm, about 20 minutes. Sprinkle with basil. Cut into wedges and serve.