Combine coffee and liqueur, dip ladyfingers, and arrange in a dish.

In a shallow dish, stir together the cooled strong coffee and optional coffee liqueur. Dip each ladyfinger quickly — one or two seconds per side — and line them snugly in a single layer in a serving dish.

Whip cream with powdered sugar and vanilla to stiff peaks.

In a chilled mixing bowl, whip the heavy cream with powdered sugar and vanilla until it holds stiff peaks.

Fold mascarpone into the whipped cream gently until smooth.

Spoon the room-temperature mascarpone in dollops over the whipped cream and fold carefully.

Spread half the mascarpone mixture over the ladyfingers.

Using a spatula, spread half of the mascarpone-cream over the soaked ladyfingers in an even layer.

Add a layer of fresh raspberries over the mascarpone.

Scatter the fresh raspberries evenly over the mascarpone layer.

Repeat layering with remaining ladyfingers, mascarpone mixture, and raspberries.

Repeat the coffee dip and cookie layer, then spread the remaining mascarpone cream and top with raspberries.

Cover and refrigerate for at least 4 hours or overnight.

Cover tightly with plastic wrap and chill to allow flavors to meld.

Dust with cocoa powder before serving.

Use a fine sieve to dust cocoa powder lightly over the top before serving.