Clafoutis ("cla-FOO-tee") is a rustic French dessert, something between a cake and a custard flan, that's traditionally prepared in a skillet. It's quick to prepare and can be made with just about any fresh fruit. This recipe isn't particularly sweet and has a nice, light texture. It will puff up in the oven but it will deflate after cooking (don't be alarmed). Serve warm or at room temperature with a scoop of ice cream or a dollop of whipped cream.
Butter and flour a 9-inch cast iron skillet or a 9-inch deep-dish pie pan. Arrange the blueberries in the pan and set aside.
Place the butter and half & half in a small saucepan and set over low heat. Cook just until the butter has melted, then remove the pan from the stove.
Whisk together the flour, sugar, and salt in a medium bowl. Add the eggs, whisking until smooth. Slowly add the melted butter and milk mixture, whisking to combine. Add the almond extract and lemon zest, then set the batter aside to rest at room temperature for at least 30 minutes, or up to 2 hours.
Position a rack in the middle of the oven and preheat to 425 degrees F. When the oven has come to temperature, whisk the batter once or twice and pour it over the blueberries in the prepared pan. Transfer the pan to the oven and cook until the cake has just set, about 30 minutes. Sprinkle the clafoutis with the remaining 2 tablespoons of sugar and cook until a skewer inserted into the center of the cake comes out clean, 5 to 10 minutes.
Transfer the clafoutis to a wire rack and let cool slightly before serving.