Heat oven to 350 degrees F.

Into medium-size bowl, sift together flour, cocoa powder and cinnamon.

In a large bowl, beat together the egg whites and cream of tartar on medium-high speed until frothy peaks form. Gradually beat in the sugar, 1 tablespoon at a time, until shiny stiff peaks form, about 5 minutes.

Sift half of the flour mixture over beaten egg whites; gently fold in. Repeat 2 more times, folding in the remaining flour mixture until incorporated. Spoon into large pastry bag without a tip on end. Or spoon into large plastic food-storage bag; snip off one corner.

Pipe angel food batter up to tops of indentations in two 12-cup mini cupcake pans.

Bake in 350 degrees F oven until cupcakes are dry to the touch and puffy, 15 to 20 minutes. Transfer pans to wire racks; let cupcakes cool in pans. Gently pull edge of cupcakes from sides of cups. Remove cupcakes and transfer to wire rack; let cool completely.

Topping: Heat together the chocolate chips and heavy cream in a microwave-safe bowl at high power for 1 minute. Or in a small saucepan, heat together the chocolate chips and heavy cream over low heat. Stir until mixture is smooth, using whisk, if necessary.

Carefully dip tops of cupcakes into topping, scraping off excess. Set mini cupcakes upright on waxed paper. Let stand until set. Can be kept refrigerated in airtight container for up to 1 week.