- Preheat Oven	Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper. 
- Separate Eggs	Place egg whites in one bowl and yolks in another. 
- Beat egg whites until foamy, then gradually add half the sugar until stiff peaks form. 
- Whisk yolks with remaining sugar until thick and pale (3-4 minutes). Add vanilla. 
- In a separate bowl, mix gluten-free flour, salt, and cornstarch. 
- Gently fold dry ingredients into the yolk mixture. 
- Carefully fold in beaten egg whites to maintain airiness. 
- Transfer batter to a piping bag and pipe 3-inch strips onto baking sheets. 
- Dust with powdered sugar, let sit for 5 minutes, then dust again lightly. 
- Bake for 12-15 minutes until golden. Cool completely before using. 
- Beat mascarpone, sugar, egg yolks, and vanilla until smooth. 
- In a separate bowl, whip heavy cream until soft peaks form. 
- Gently fold whipped cream into mascarpone mixture in batches. 
- Refrigerate filling while preparing coffee soak. 
- Combine coffee, rum/marsala (if using), and sugar in a shallow dish. Stir until sugar dissolves. 
- Use an 8×8-inch dish or 9-inch round dish. 
- Quickly dip ladyfingers in coffee (1 second per side). 
- Arrange a layer of dipped ladyfingers in the dish. 
- Spread half the mascarpone mixture evenly over ladyfingers. 
- Repeat with another layer of dipped ladyfingers. 
- Spread remaining mascarpone mixture evenly over the top. 
- Use an offset spatula to smooth the top. 
- Cover with plastic wrap and refrigerate at least 6 hours, preferably overnight. 
- Before serving, dust generously with cocoa powder. 
- Add dark chocolate shavings if desired. Serve chilled.