Place the ladyfingers in a food processor and pulse until they form fine crumbs. Transfer to a medium mixing bowl.

Add the softened mascarpone cheese, powdered sugar, cooled espresso, and vanilla extract to the bowl with the crumbs.

Using a spatula, mix everything together until a cohesive, thick dough forms. It should hold its shape when pressed.

Using a small cookie scoop (about 1 tablespoon), scoop the dough and roll it between your hands to form smooth balls. Place on a parchment-lined baking sheet.

Chill the truffles in the refrigerator for at least 1 hour, or in the freezer for 30 minutes, until very firm.

Once chilled, melt the white chocolate in a double boiler over gently simmering water, or in the microwave in 20-second bursts at 50% power, stirring until smooth. Stir in coconut oil if the chocolate is too thick.

Using a fork, dip each chilled truffle into the melted white chocolate, tapping off any excess. Return the coated truffle to the parchment paper.

While the white chocolate is still wet, generously dust the tops of the truffles with cocoa powder using a fine-mesh sieve.

Allow the chocolate to set completely before serving. Store leftovers in an airtight container in the refrigerator.