In a large mixing bowl, add the mascarpone cheese, vanilla extract, and sugar, and mix with an electric hand mixer until well combined.
Add the cold heavy cream and mix until the mixture thickens.
Add the strawberry jam and ground freeze-dried strawberries and mix until well combined.
Dip the ladyfingers quickly in the milk (1-2 seconds) and lay them in an even layer in the 10.5-inch x 7.5-inch baking pan.
Top the soaked ladyfingers with half of the mascarpone mixture and smooth it out with a spatula.
Add another layer of the dipped ladyfingers and top it with the remaining mascarpone mixture. Smooth it out with an offset spatula.
Cover the pan tightly with plastic wrap and refrigerate for at least 4 hours.
Sprinkle strawberry powder (from 1 cup of ground freeze-dried strawberries) on top of the tiramisu and top it with sliced strawberries. Serve and enjoy.