Preparation

1. For the Pâte Sablée Tart Shell: In a stand mixer, whisk the butter until smooth and slightly whipped. Scrape the sides of the bowl and beater and add the confectioners’ sugar. Whisk the butter and sugar until smooth and buttercream-like. Add egg yolk and whisk again until the mixture is combined. Add the flour to the butter mixture and mix until the mixture is crumbly. Add cream or milk and mix on low until the mixture balls together.
2. Preheat oven to 191°C (375° F). Turn out onto a lightly floured surface and gather the dough into a ball. Wrap the dough in plastic wrap and refrigerate for about 10 minutes. Once chilled, roll out the dough to desired thickness and place or press it into an 20-23 cm (8-9 inch) tart pan. Generously perforate the base and sides of the tart shell with a fork, and place the shell into the freezer, until about 10 minutes before baking. Place pie weights in the bottom of the crust to reduce the rise of the crust, and bake for 12-13 minutes until the crust is slightly golden, 12-13 minutes. If you are left with extra dough, shape and bake into sablée cookies for decoration.

3. For the Peach Bellini Filling: Chop the peaches and add to a medium saucepan. Add the champagne, elderflower liqueur, if using, and sugar. Heat the mixture on low stirring occasionally. Once the peaches are soft and jam-like transfer the mixture to a blender or food processor, and blend until the mixture is smooth and liquid. Separate 118 ml (1/2 cup) of the blended mixture into a small bowl and mix in the unflavored gelatin; allow it to bloom for about five minutes. When the gelatin mixture is congealed, add the gelatin mixture to the hot peach filling and blend until fully smooth. Pour the filling directly into the baked tart shell and place in the refrigerator for about six hours, or until the filling is completely set.

4. Top the tart with piped whipped cream and other decorations of your choice.