Directions

Prepare Filling: Using a hand mixer or whisk whip together the mascarpone cheese, cream, and 1/4-cup sugar. Add the cream a little at a time. You are looking for a sour cream consistency, very smooth with no lumps. Mix in 1/4-cup basil chiffonade at the very end until just incorporated. Refrigerate filling, covered, until you are ready to assemble the tart. Make Tart Shell: Whisk together the flour with the cornmeal, and salt in a large bowl. In a smaller bowl mix egg yolk, cream, and vanilla. In a 3rd bowl cream the butter and 1/4 cup sugar together using an electric mixer fitted with the paddle attachment. Mix them together on medium speed until they form a pale and fluffy paste, 2 to 3 minutes. Add the egg yolk mixture and mix them together on medium-low speed until well combined. Working in 3 additions, add flour mixture to the bowl until just combined. I find these additions easier to work with using a wooden spoon so as not to over mix the dough. Working on a piece of plastic wrap shape dough into an oblong shape that is roughly the size of your tart tin (13 3/4-by-4 1/4-by-1-inch). Add an additional piece of plastic on top and roll a rolling pin over the top to form a smooth flat piece of dough about 1/4-inch thick. Close up the plastic wrap and move dough to the refrigerator. Refrigerate until cold, about 30 minutes, before using. Preheat oven to 375 degrees. Remove the dough from the refrigerator and peel off the top layer of plastic wrap. Invert the dough into the tart tin. It does not matter if it breaks or does not fit perfectly. Because you can press dough together and finish the shaping in the tart tin. The type with a removable bottom works best. Trim edges of dough flush with pan. Refrigerate until firm, about 30 minutes. Bake about 18 minutes until golden and crisp. Let cool completely on a wire rack. Make the Peaches: Peel the peaches. This can be accomplished easily if you blanch the peaches first. This will loosen their skin and the task is not nearly as messy as it would be with a knife. Prepare an ice bath in a large bowl large enough for all the peaches. With a paring knife, lightly score an X onto the bottom of each peach. Bring a large pot of water to a boil. Carefully drop the peaches into the water for 1 to 2 minutes. Using a slotted spoon, move the peaches into to an ice-water bath to stop the cooking. Once the peaches have cooled, the skin should peel off easily. You may need to get it started with a paring knife, but most of the skin can be removed with your hands. Cut the peaches in half and remove the pits. Cut each half into 4 or 5 evenly sized wedges. Stir together the peach wedges, remaining 1/4-cup sugar, 1 tablespoon water, and remaining 1/4-cup basil in a medium sized saucepan with a lid, set over medium heat. Cook covered, stirring occasionally, until the peaches have softened, become a uniform color and released their juices, about 6 minutes. Let the peaches cool completely in the syrup. If necessary, right before assembling remove the peaches using a slotted spoon and continue to cook the juices until they have thickened to a syrup. Assemble the Tart: Spoon mascarpone filling into tart shell. Top with the peaches in an attractive manner, spooning the thickened juices over the top. Garnish with additional basil sprigs.