If making homemade buttermilk, add 1 tbsp of white vinegar to a liquid measuring cup and fill to the 1 cup mark with milk. Let sit 5 mins and refrigerate to get cold.
For the dough
Whisk together flour and salt in a large mixing bowl. Add cold butter cubes to flour and break apart using your fingers until they're the size of peas. Some flat shard-like pieces are good too. Add 3 tablespoons cold buttermilk and stir with a wooden spoon to combine. Add in one tablespoon at a time til the dough starts to come together (some dry patches are okay). I usually use about 5-6 tbsp. Transfer dough to a flat, lightly floured surface and knead for a few minutes til dough comes together, nicely. Form into a flat disk, cover with plastic wrap, and refrigerate at least one hour to overnight, or up to a week!
For the galette
Preheat oven to 400 degrees F. Take goat cheese and dough out of fridge to let warm up to room temp or until pliable, while you make the filling.
Cut peaches into slices or wedges. Pit the cherries by using a cherry pitter or poking a straw through the stop and pushing through so the pit comes out the bottom. Or use one of these methods. Cut in half and leave some whole. Zest and juice lemon for filling.Add all filling ingredients (except goat cheese and pepper jelly) to a large mixing bowl, stir to combine, and let sit to allow flavors to meld while you prep dough.
When dough is pliable, gently roll it out to ⅛ inch thick on a floured surface. Make sure to rotate dough clockwise every few strokes to prevent it from sticking to counter, dusting with more flour if necessary. Transfer dough to a baking sheet lined with a silicone mat by carefully wrapping the dough around a rolling pin and placing it onto the pan. Spread a layer of goat cheese onto the dough leaving 1-2 inches for the crust, followed by a layer of pepper jelly. Add fruit with juices to the center of the galette and fold edges up around the fruit. Pop in the fridge for 15 mins.
Brush edges with beaten egg and sprinkle with turbinado sugar. Bake for 45-60 mins. Make sure the filling gets a chance to bubble to activate the cornstarch so that the juices thicken. It's okay if juices leak onto pan from the filling. It won't ruin your galette, but you will have to clean your pan with some extra elbow grease!It’s done when it’s bubbling and the edges are golden brown. Use tin foil to cover edged if they start to brown too quickly. Garnish with fresh basil and serve with honey.
Make sure butter and buttermilk are very cold before making the dough. I like to cut the butter into cubes and pop it in the freezer, along with the buttermilk, for 10 mins before starting the dough. See all my tips for flaky pie dough above.