Dust the bottom of an 8x8x3-inch or 9x7x3-inch pan with 1 Tablespoon cocoa powder. Set aside.
Prepare egg whites: Set a grease-free, metal bowl over a pot filled 2 inches with simmering water. Whisk egg whites and ¼ cup sugar until stiff. Set aside.
Make mascarpone filling: In a separate bowl, beat egg yolks and remaining ½ cup sugar until light and fluffy, about 3 minutes. Gently fold in the mascarpone, then the egg whites.
Prepare coffee: Whisk together cooled coffee and marsala (or alcohol of choice).
Prepare ladyfingers: One at a time, dip the lady fingers in the coffee, about 1 or 2 seconds per side. If the ladyfingers soak in the coffee too long they will fall apart or create a watery tiramisu. Arrange ladyfingers in the bottom of the prepared baking dish. If necessary, break ladyfingers in half to fill any gaps.
Layer tiramisu: Spread half of the mascarpone mixture over the first layer of lady fingers. Repeat once more so there are two layers of ladyfingers and mascarpone (final layer is mascarpone on top).
Chill tiramisu: Cover the tiramisu dish securely with plastic wrap. Chill 8 to 12 hours or overnight. Before serving, dust with remaining 1 tablespoon cocoa powder.
Store tiramisu covered in the refrigerator for up to 4 days.Freeze tiramisu after it has been chilled. I suggest cutting the tiramisu into individual servings first. Freeze each serving for 2 ours so it hardens. Then, individually wrap the servings in plastic wrap and aluminum foil. Freeze for up to 3 months and defrost in the refrigerator for 6 hours before serving.