3 cups chilled heavy cream
1/2 cup plus 1 tablespoon sugar
1 cup mascarpone cheese (about 9 oz) at room temperature
1 (9-oz) box chocolate wafers such as Nabisco Famous
1 tablespoon instant-espresso powder
Beat 2 cups cream with 6 tablespoons sugar in a bowl with an electric mixer at medium speed until it just holds soft peaks, 2 to 4 minutes. Reduce speed to low, then add mascarpone and mix until combined.
Spread 1 1/4 cups mascarpone mixture evenly in bottom of springform pan and cover with 14 wafers, slightly overlapping if necessary. Spread with another 1 1/4 cups mascarpone mixture, followed by 14 more wafers arranged in the same manner. Spread remaining mascarpone mixture on top. Smooth top with a metal offset spatula, then cover pan with foil and freeze until firm, about 1 hour. Transfer from freezer to refrigerator and chill, covered, until a sharp knife inserted into center cuts through softened wafers easily, about 8 hours.
Pulse remaining chocolate wafers in a food processor until finely ground.
Beat remaining cup cream with espresso powder and remaining 3 tablespoons sugar using electric mixer at medium speed until it just holds stiff peaks, about 3 minutes.
Remove foil and side of pan and frost cake all over with espresso cream. Sprinkle edge of top lightly with wafer crumbs. Serve cold.
Cake, without espresso cream, can be chilled up to 2 days.
Cake can be frosted with espresso cream 4 hours ahead and chilled, loosely covered with foil.