Make the lemon syrup: Add water, sugar and lemon peel to a medium saucepan and bring to a boil over medium heat. Simmer for 1 minute, or until the sugar dissolves. Remove from the heat, stir in lemon juice and Limoncello, if using, and set aside. Allow to cool and remove peels.
Make the cream: Combine sugar and water in a small saucepan set over medium heat. Bring to a boil and simmer until sugar dissolves, 1 minute. Place egg yolks in the bowl of a stand mixer fitted with the whisk attachment, and whisk on medium-low. With the mixer running, slowly and very carefully drizzle in the hot sugar syrup. Increase the mixer’s speed to medium-high and beat until the bowl is no longer hot to the touch and the mixture has tripled in size, about 5 minutes. Turn mixer to medium speed and add mascarpone in a few large dollops, letting each incorporate before adding the next. Add confectioners sugar and beat until just combined and smooth.
In a separate clean and chilled bowl, beat cream and vanilla to stiff peaks. Using a spatula, gently fold whipped cream into the mascarpone mixture until fully incorporated. Set aside.
Pour lemon syrup into a shallow bowl and dip ladyfingers, turning once to coat for a few seconds, allowing them to absorb some of the syrup. Line the bottom of the 9x13 baking dish with a single layer of the ladyfingers. If you have a lot more than half the syrup left, drizzle an extra two or three tablespoons syrup over the ladyfingers in the dish.
Top ladyfingers with half of the mascarpone mixture and smooth the surface with an offset spatula or butter knife. Place a layer of sliced strawberries all over the mascarpone mixture, reserving the remaining strawberries for the top.
Repeat with the second layer of dipped ladyfingers, and top with the remaining mascarpone mixture. Smooth the top.
Decorate the top with the remaining strawberries. For a flower pattern, work from the center-out and angle the strawberries slices, continuing around the dish until you have a flower-like pattern. Refrigerate for 4 to 6 hours and up to 1 day. Top with a sprinkle of edible flowers, if desired, then slice and serve.