Sunken Chocolate-Orange Cupcakes

Preheat oven to 350°F. Place almonds in processor. Using on/off turns, blend until nuts are coarsely ground.

Line 12-cup muffin pan with paper liners. Microwave chocolate and butter in small bowl on high 30 seconds; stir. Microwave until almost melted, about 30 seconds longer. Stir to combine. Cool chocolate mixture until barely lukewarm but still liquid, about 5 minutes. Whisk egg yolks and 3/4 cup sugar in large bowl until blended. Mix in orange peel, ground almonds, and chocolate mixture.

Using electric mixer, beat egg whites and remaining 1/4 cup sugar in another large bowl until mixture is thick and glossy and peaks form. Fold egg-white mixture into chocolate mixture in 3 additions. Divide batter among prepared muffin cups (about 1/3 cup batter in each). Bake until edges are firm and tops are cracked all over, about 16 minutes for very soft cake or about 22 minutes for firmer cake. Serve warm with whipped cream or ice cream. DO AHEAD: Can be made 2 days ahead. Cover and chill. Rewarm in microwave in 10-second intervals before serving.