A fool is an ideal make-ahead dessert. For a very creamy, thick fool with defined streaks of puree, serve it the same day. For a more ethereal, mousselike texture, you can chill it overnight. The color from the puree will gradually bleed into the whipped cream as the fool chills, but it will still be pretty.
- 2 cups frozen wild blueberries, thawed, or fresh blueberries
- 2 tablespoons fresh lemon juice (from 1 lemon)
- Scant 1/4 teaspoon ground cinnamon
- 7 tablespoons sugar, divided
- 1/4 teaspoon coarse salt
- 2 cups heavy cream
Combine blueberries, lemon juice, cinnamon, 4 tablespoons sugar, and salt in a medium saucepan and bring to a boil over high heat. Reduce heat and simmer until blueberries burst and become very soft, about 8 minutes. Transfer mixture to a food processor and puree. Pour into a fine sieve set over a bowl, stirring and pressing on solids to remove as much liquid as possible. Discard solids and refrigerate puree until cold and thickened slightly, at least 1 hour and, covered with plastic wrap, up to 1 day.
Whisk or beat cream with remaining 3 tablespoons sugar to soft peaks in a large, wide bowl. Drizzle puree evenly over cream and fold cream over puree twice with a large rubber spatula or wooden spoon just until puree is streaked throughout cream. (Do not overmix.) Transfer to a large serving bowl or individual serving dishes and refrigerate until set, at least 2 hours and, covered with plastic wrap, up to 1 day. Serve cold.