Keep all ingredients, especially butter and water, cold to ensure a flaky crust., Do not overwork dough; pulse just until it holds together., Add ice water sparingly; dough should barely come together., Use a rimmed baking sheet to catch any juices and prevent oven messes., Instant oats under the filling help prevent soggy crust by soaking excess juices., Freezing the galette before baking keeps the crust crisp and prevents spreading., If crust browns too quickly, tent loosely with foil mid-baking to prevent burning., Substitute vanilla bean with 1 teaspoon pure vanilla extract if needed., For vegan version, use cold coconut oil or vegan butter and brush with non-dairy milk instead of egg wash., For gluten-free, replace flour with 1:1 gluten-free flour blend; watch baking time and texture differences., The filling can be prepared a few hours in advance and kept refrigerated, stirring before assembling., Dough can be made up to 2 days ahead or frozen up to 3 months., Store finished galette at room temperature up to 24 hours or refrigerated up to 3 days, reheating in oven to restore crispness., Freeze baked galette whole or in slices up to 2 months; reheat from frozen at 325°F until warmed.