Step 1: Prepare the strained yogurt. Line a fine-mesh sieve with cheesecloth or a clean kitchen towel and place it over a bowl. Spoon the Greek yogurt into the sieve. Cover and refrigerate for at least 4 hours, or preferably overnight, to allow excess whey to drain. This step is crucial for a thick, creamy consistency.
Step 2: In a large bowl, combine the strained Greek yogurt, softened mascarpone cheese, granulated sugar, and vanilla extract. Beat with an electric mixer on medium speed until smooth, creamy, and well combined. Taste and adjust sugar if desired. This is your yogurt-mascarpone cream.
Step 3: In a shallow dish, combine the cooled espresso (or strong coffee) and coffee liqueur (if using). Stir gently.
Step 4: Quickly dip each ladyfinger into the coffee mixture, one at a time, for just 1-2 seconds per side. Be careful not to over-soak them, or they will become soggy.
Step 5: Arrange a single layer of dipped ladyfingers in the bottom of an 8x8 inch (20x20 cm) square dish or a similar sized serving dish (approximately 2-quart capacity). You may need to break some ladyfingers to fit.
Step 6: Spread half of the yogurt-mascarpone cream evenly over the layer of ladyfingers.
Step 7: Arrange a second layer of dipped ladyfingers over the cream.
Step 8: Spread the remaining half of the yogurt-mascarpone cream over the second layer of ladyfingers, ensuring the top is smooth and even.
Step 9: Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or ideally overnight, to allow the flavors to meld and the dessert to set properly. This chilling time is essential for the perfect Yogurt Tiramisu.
Step 10: Just before serving, dust generously with unsweetened cocoa powder using a fine-mesh sieve.
Step 11: Garnish with optional chocolate shavings, fresh berries, or mint leaves. Slice and serve your delicious Yogurt Tiramisu chilled.