Individual gratins of fresh apricots and raspberries make a terrific early summer dessert. Here we've cloaked the fruit with a dollop of almond-scented custard for a bit of heady richness. These gratins can be assembled up to 6 hours in advance. If you don't have individual gratin dishes, use a 7 x 11-inch baking pan.
Position a rack in the middle of the oven and preheat to 350 degrees F.
Butter the ramekins with some of the cubed butter; reserve the remainder.
Place the slivered almonds in the bowl of a small food processor and pulse to chop fine. Add the powdered sugar and process until the almonds are finely ground into a flour-like meal. Transfer the almond-sugar mixture to a bowl.
In another small bowl, whisk together the eggs, cream, almond extract, and salt. Add the liquid mixture to the almond-sugar meal and stir to combine.
Place the apricots in a bowl and toss with the lemon juice. Divide the apricots among the buttered gratin dishes. Add the raspberries, dividing them among the dishes.
Place the gratin dishes on a rimmed baking sheet. Pour the custard over the fruit. (If making ahead, cover the gratins with plastic wrap and refrigerate for up to 6 hours before continuing with the recipe.) Sprinkle each gratin with some of the sliced almonds. Divide the reserved butter between the dishes, dotting the top of each gratin with a few pieces.
Bake until the apricots are tender when pierced with the tip of a knife, about 30 minutes. Remove the baking sheet from the oven.
Place a rack about 5 inches from the broiler and preheat the broiler. Return the gratins to the oven on the baking sheet and broil until the almonds turn light golden, about 2 minutes.
Cool the gratins on a wire rack to room temperature before serving.