Make the crust. In a medium bowl, whisk together flour, sugar, baking powder and salt. Gently toss the butter in the flour mixture until coated and quickly mix until just incorporated.
Slowly add half of the ice water mixture and stir lightly with a fork until the flour is evenly moistened and the dough starts to come together. If you grab a small piece of dough and press it slightly with your hand, it should hold together. Shape the dough into a round disc, tightly wrap it in plastic wrap, and chill for at least 2 hours (up to 3 days in the refrigerator and up to a month in the freezer).
Prepare the tomatoes: Place the tomato slices, thyme and shallot in a large bowl and gently toss with the salt. Set aside for 30 minutes to draw excess moisture out of the tomatoes. Drain and transfer to paper towels or kitchen towels to soak up additional moisture while you assemble the galette.
Make the pimento cheese: whisk together the mayonnaise, cayenne, hot sauce and salt in a medium bowl. Add the cheese and pimentos and gently mix until combined. The pimento cheese can be made up to 3 days in advance and stored tightly covered in the refrigerator. I recommend removing it about 30 minutes before using so that it will spread easily onto the dough.
Assemble the galette: Preheat your Artisan Fire Pizza oven to 375 degrees or your indoor oven to 400 degrees F. Line a half sheetpan with parchment paper or a Silpat.
In a small bowl, whisk together the egg and 2 tablespoons of cold water until smooth, set aside.
Place the chilled dough on a lightly floured surface. Dust the top with flour and use a rolling pin to roll it out into a 12-inch circle about ⅛-inch thick. As you work, rotate the dough a quarter turn every few rolls to prevent it from sticking to your work surface. I also like to dust the top of the dough with flour and flip it over a few times during the rolling process.
To transfer the rolled-out dough to the prepared baking sheet, roll the dough over your rolling pin and unroll it onto the baking sheet. Spread the pimento cheese mixture in the center of the dough, leaving a 1-inch border all around. Arrange the tomatoes on top and fold the edges of the dough over the edges of the tomatoes, leaving the center of the filling exposed. Brush the crust with the egg wash and sprinkle with some flaky salt.
Bake for 12 to 15 minutes in the pizza oven or 25-30 mins in an indoor oven, or until the crust is golden brown and the cheese is bubbling underneath the tomatoes. Make sure to turn the sheet pan (using heavy duty grill gloves) several times during the baking for even browning.
Remove from the oven, garnish with the basil and allow the galette to cool for 10 minutes on the baking sheet before slicing.
Grillmaster’s Tip: Turning the dish every 5 minutes when cooking in the Artisan Fire Pizza Oven for even cooking and browning. We also recommend placing an oven thermometer on the floor of the Pizza Oven to gauge the temperature level.
