Preheat your oven to 350°F and brush a 9-inch ceramic baking dish with melted butter. I always do this while gathering ingredients so I don't forget—it creates a thin golden layer underneath that you'll taste in every bite. The butter anchors flavor before anything else even enters the dish.

Whisk together flour, sugar, eggs, milk, remaining melted butter, lemon zest, vanilla bean paste, and salt in a large bowl until smooth. Use a fork or whisk—you want the mixture thin and pourable, almost like heavy cream. I confess I always taste a tiny spoonful (raw eggs and all) because it smells incredible, and this step builds confidence you've got the ratio right.

Pour batter into your prepared dish and let it sit for 3 minutes so flour fully hydrates. This pause matters because hydrated flour produces a custard texture rather than a cakey crumb. Scatter fresh berries evenly across the surface—don't press them down, just let them rest on top where they'll stay visible and warm through gently.

Place the dish on a middle oven rack and bake for 32–35 minutes until the custard puffs around the berries and turns light golden. You'll see the edges rise while the center stays slightly soft—that's exactly what you want. I learned this the hard way after overbaking my first summer berry clafoutis cozy warm, so trust the time more than your eyes.

Remove from the oven and let cool for 5 minutes—this resting time prevents the whole thing from collapsing. The warm custard continues setting gently without overcooking the center. Dust with powdered sugar just before serving for that café-style finish.

Slice into 6 wedges and serve while the custard still feels warm. Comfort summer baking demands warmth, so don't refrigerate and reheat before eating. Each slice should feel tender with berries that maintain their structure.