Vanilla beans are one my most favorite ingredients because they just add something special to recipes. I use them for creme brûlée, ice cream, pudding and homemade vanilla extract. In my opinion, there is nothing more beautiful than a custard or filling speckled with tiny flecks of vanilla bean seeds.
Vanilla beans used to be reserved for the most precious of recipes and occasions. But now that they are readily available, you can use them whenever you want in many recipes. (Many grocery stores carry them, but I prefer to order my vanilla beans in bulk online.) They come from all over the world, so try different varieties and see which one is your favorite. But all vanilla beans should be soft and pliable.
To use a vanilla bean, carefully slice the bean in half lengthwise with a paring knife.
Use the back of the paring knife to gently scrape out the seeds. You will have a pool of sticky, black vanilla beans.
To make the tart, start by mixing the crust. Put flour, sugar, salt, lemon zest and vanilla beans in the bowl of a stand mixer. Add the butter pieces; mix until the mixture begins to look like peas. In a small bowl, whisk together the egg yolks and limoncello; add to the mixer. As soon as it comes together, turn the dough out onto a lightly floured surface.
Form the dough into a ball, and wrap in plastic wrap. Let chill in the fridge for 1 hour or up to 2 days. (The dough can also be frozen for 1 month.)
When ready to use, roll out the dough and lay in a 9-inch tart pan. Bake at 425° until golden brown, about 20 minutes. While the crust cools, start on the filling.
Put the mascarpone, cream, limoncello, sugar, lemon zest and vanilla beans into the bowl of an electric mixer fitted with the whisk attachment. Whisk until soft peaks form.
Spread the filling into the crust and top with raspberries.
Melt the jelly, and brush over the fruit. Keep in the fridge until you are ready to serve.