Chocolate Orange Cheesecakes

Put oven rack in middle position and preheat oven to 350°F. Butter muffin cups. Grind wafers to a fine powder in a food processor. Mix together wafer crumbs, 2 tablespoons butter, and 2 tablespoons brown sugar in a bowl with a rubber spatula until combined well. Divide crumbs among muffin cups, then firmly press onto bottom and a little up side of each cup with your fingertips or with bottom of an ⅛-cup measure by twisting measure. Bake 5 minutes, then transfer to a rack and cool in muffin pan 10 minutes. Gently rotate crusts with your fingertips to loosen and turn out onto rack. Beat together cream cheese, zest, and remaining brown sugar (3 tablespoons plus ⅓ teaspoon ) with an electric mixer at medium-high speed until fluffy. Beat cream in another bowl with cleaned beaters until it just holds stiff peaks. Stir about one third of whipped cream into cream cheese mixture to lighten, then gently fold in remaining whipped cream until just combined. Mound filling into crusts with a spoon (or pipe filling into crusts with a pastry bag) and serve, or chill until ready to serve.