Begin by preheating your oven to 350°F (175°C). This step is crucial for ensuring that your Grape Clafoutis bakes evenly.
Grease your pie dish with a bit of butter. This will prevent the clafoutis from sticking to the dish once baked.
In a large mixing bowl, whisk together the 4 large eggs, 1 cup of milk, 1 teaspoon of vanilla extract, and ½ cup of melted butter until smooth.
In a separate bowl, sift together the 1 cup of all-purpose flour and ½ cup of granulated sugar. Gradually add the dry mixture to the wet ingredients, whisking until just combined. Be careful not to overmix; a few lumps are perfectly fine.
Gently fold the washed and dried grapes into the batter, ensuring they are evenly distributed.
Pour the batter into the prepared pie dish. Bake in the preheated oven for 35 to 40 minutes, or until the edges are golden and the center is set. A toothpick inserted in the center should come out clean.
Once baked, remove from the oven and let it cool for a few minutes. Grape Clafoutis can be served warm or at room temperature. Dust with powdered sugar if desired, and enjoy!