The French believe that leaving the pits in the cherries makes the clafoutis more flavorful. It’s certainly easier on the cook, and provides lots of opportunity for playful pit-spitting and juicy red fingers when you serve the dessert. The squeamish may pit their cherries, but if you want the real deal, leave your cherries intact. As it were.
(And so you’ll be able to pronounce it when you serve it, it's klah-foo-tee, with the accent on the last syllable.) —Abra Bennett
Remove stems from the cherries, but leave the pits in. (Again, if you're squeamish, you may pit your cherries; just know that the end result will taste a little different.)
For the caramelized cherries: In a large nonstick pan, melt the 1 tablespoon butter and 1 tablespoon sugar. Add the cherries and let them slowly caramelize over medium-low heat, stirring occasionally, until the juices begin to run and the fruit looks glazed, about 10 to 15 minutes. Generously butter a 9×13-inch pan and place the cherries in it, distributing them evenly.
Preheat oven to 350°F and while the cherries are cooling a bit, prepare the batter: Beat the eggs, yolks, and salt together very well, using a whisk. Beat in the sugar, then sprinkle in the flour while continuing to whisk until batter is smooth.
In a separate bowl, mix together the milk, melted butter, and vanilla and add to the dry mixture, stirring until thoroughly combined. Pour the batter carefully over the cherries in the buttered pan, being careful to keep the fruit evenly distributed. Generously dot the top with little slivers of the extra butter. Bake for about 45 minutes, or until the top is puffed and deeply golden.
Dust with powdered sugar if you'd like, then serve warm or at room temperature, warning your guests about the pits.