MAKE THE PASTRY: Spray a 10-inch fluted tart pan with a removable bottom with cooking spray. In a food processor, pulse the flour, sugar, and salt until blended. Add the butter and cream cheese and pulse until moist crumbs form. Scrape the crumbs into the tart pan and press them over the bottom and up the side in an even layer. Refrigerate until firm, 20 minutes.

Preheat the oven to 325 degrees. Line the pastry with foil and fill with pie weights or dried beans. Bake for 25 minutes, until just set. Carefully remove the foil and weights and bake for 15 minutes longer, until the crust is completely set and lightly golden.

MEANWHILE, MAKE THE FILLING: Bring a large saucepan of water to a boil and fill a large bowl with ice water. Score the peach bottoms with an X. Add a few peaches at a time to the boiling water and blanch for 10 seconds; transfer to the ice water. Drain and peel the peaches. Cut 6 peaches into quarters and slice the remaining 4 peaches.

In a bowl, using an electric mixer, beat the butter with the 3/4 cup of sugar until creamy. Add the eggs and vanilla and beat until smooth, then beat in the flour, cornmeal, cinnamon, and nutmeg. Spread the filling in the crust and arrange the peach quarters on top in 2 concentric circles. Sprinkle the peaches with sugar and bake for 1 hour and 40 minutes, until the filling is firm and lightly browned. Transfer to a rack to cool.

Remove the tart ring and slide the tart onto a plate. Top with the sliced peaches, sprinkle with sugar and serve.