1/2cupwhole grain cornmealuse fine or medium grind
1/2teaspoonkosher salt
1/3cupcold buttermilklowfat is fine, plus extra as needed
2tablespoonsraw honey
for the filling
1tablespoonplus 1 teaspoon olive oil
2large leeksthinly sliced (whites and light green parts only)
2 to 3ouncesprosciuttosliced into small dice
2ouncesgoat cheesecrumbled
1small zucchinithinly sliced into half moons
1small yellow summer squashthinly sliced into half moons
1large handfula dozen or so heirloom cherry tomatoes (slice the larger tomatoes into thirds, smaller in half)
1tablespoonminced fresh basil
1tablespoonminced fresh cilantro
1tablespoonminced fresh dill
salt and freshly ground black pepper
Instructions
make the crust
Preheat oven to 350°F and line a baking sheet with parchment paper.
Place the butter cubes in the freezer while you prep the dry ingredients.
Pour the flour, cornmeal, and salt into the bowl of a food processor and pulse a few times to combine. Add the new very cold butter cubes and use long pulses until the mixture is crumbly. Add the buttermilk and honey, and process until the dough comes away from the sides of the bowl and clumps together in the bowl. (In the unlikely even that the dough is still dry and crumbly, add more buttermilk, one tablespoon at a time, until the dough comes together.)
Turn out the dough onto a floured board. Roll out into a circle about 1/8" deep. It's okay if the edges are a bit rough. Use a bench knife to gently lift the round from the board and transfer to the parchment paper.
prepare the filling and assemble the galette
Heat 1 tablespoon olive oil in a medium skillet over medium heat until the oil shimmers. Add the leeks and saute until soft with lightly golden edges. Add the prosciutto and mix into the leeks. Remove skillet from the heat to cool for a few minutes. Spread the leek mixture over the cornmeal crust, leaving 1 1/2" clear around the edges. Sprinkle most of the goat cheese over the leek mixture, reserving about 1/4 for topping.
Shingle the zucchini and squash over the cheese.
Gently toss the sliced tomatoes with 1 teaspoon olive oil and a big pinch each of salt and pepper. Layer the tomatoes over the squash. Top with the remaining goat cheese, plus a few sprinkles of the herbs.
Fold the edges of the galette over the filling. Do this in sections, pleating the overlap as you work your way around the crust (repair any tears by just pinching the dough together).
Bake for 45 minutes to an hour, until the crust is golden brown and the tomatoes are gently roasted (slightly shriveled). Remove and sprinkle with the remaining herbs. Let cool for 5 minutes before slicing.