Pour the heavy whipping cream into a large mixing bowl and whip on medium speed with a hand mixer, adding the sugar and vanilla extract gradually until stiff peaks develop. Gently fold in the mascarpone cheese until the mixture is smooth and well-blended, then set aside. Combine the espresso and coffee liqueur in a shallow bowl. Briefly dip each ladyfinger into the coffee mixture, ensuring they are moistened but not soggy, and arrange them in a single layer at the base of an 8x8 inch dish. Spread half of the mascarpone mixture evenly over the ladyfingers. Repeat with a second layer of dipped ladyfingers and finish with the remaining mascarpone cream, smoothing it to the edges. Using a fine mesh sieve, dust the surface generously with cocoa powder. Refrigerate the tiramisu for a minimum of 3–4 hours or overnight to allow the flavors to meld.