In a medium saucepan, combine the granulated sugar, water, and the juice and zest from 1 lemon. Bring to a gentle simmer over medium heat, stirring until the sugar dissolves completely, about 5 minutes. Remove from heat and let the syrup cool completely to room temperature. This is important so it doesn't melt your mascarpone!

In a large mixing bowl, using an electric mixer, whip the cold heavy cream until soft peaks form. Don't overmix it, or it could turn to butter!

In a separate bowl, gently whisk the room temperature mascarpone cheese until smooth. Add the powdered sugar, zest of the second lemon, and vanilla extract, mixing until just combined. Fold about one-third of the whipped cream into the mascarpone mixture to lighten it, then gently fold in the remaining whipped cream until no streaks remain. Be careful not to deflate the cream too much.

Quickly dip each ladyfinger into the cooled lemon syrup, just for a second or two on each side – you don't want them soggy! Arrange a single layer of soaked ladyfingers on the bottom of a 9x13 inch baking dish. Break them if needed to fit snugly.

Spread half of the mascarpone cream evenly over the ladyfingers. Scatter about half (0.75 cups) of the fresh raspberries over the cream layer.

Repeat with another layer of syrup-dipped ladyfingers, then the remaining mascarpone cream. Top with the remaining fresh raspberries.

Cover the dish with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld and the tiramisu to set. Before serving, you can garnish with a few extra fresh raspberries and a little lemon zest for a pop of color.