In a small pot over medium heat, heat cream and espresso until bubbles form around the edges. Let cool 10 minutes.

Place 2 cups white chocolate chips in a large heatproof bowl. Using a fine-mesh sieve, strain cream into bowl over chips (if a few espresso powder grains sneak through, it’s all right); discard solids.

Set bowl with chips over a medium pot of barely simmering water, making sure bottom of bowl does not touch water. Cook, stirring constantly, until chocolate is nearly melted. Remove from heat and stir until smooth.

Add mascarpone and salt and whisk to combine. Cover and refrigerate until firm, at least 2 hours or up to overnight.

Roll ganache into 24 (1") balls (a rounded tablespoon each). Arrange on a parchment-lined sheet. Freeze until solid, at least 30 minutes or up to overnight.

In a small heatproof bowl, microwave 1 tablespoon oil and remaining 1 cup white chocolate chips in 20-second increments, stirring between each, until melted and smooth.

Drop one ball into melted chocolate, spooning over to coat, and return to baking sheet. Shave dark chocolate on top. Repeat with 7 more balls.

In heatproof bowl, microwave semisweet chips and remaining 1 tablespoon oil in 20-second increments, stirring between each, until melted and smooth. Repeat dipping process with 8 more balls. Sprinkle with ladyfingers.

Place cocoa powder in a small bowl. Roll remaining 8 balls in cocoa powder and place on sheet. Refrigerate truffles until firm, at least 30 minutes or up to overnight.