Bake until just set, 18 to 20 minutes. (The center should still be a little jiggly—it will firm up as it cools.)
Let cool to room temperature in the pan on a wire rack, about 1 1/2 hours. Gently lift out of the pan all in one piece using the edges of the foil. Cut into 9 squares. Garnish with fresh fruit and dust with confectioners’ sugar, if desired, just before serving.