Raspberry Peach Tarts with Oat Press-In Crust

Steps

1. Make the dough first: whisk the flour, oats, brown sugar and salt in a large bowl, then rub in the butter with your fingertips until it looks like coarse crumbs with some pea-sized pieces.
2. Sprinkle in the ice-cold water a little at a time, tossing with a fork, until the dough holds together when squeezed.
3. Divide the dough: weigh it and set aside half for the two press-in crusts, then shape the remaining half into two equal flat discs for the lids. Wrap the lid discs and chill them for 30 minutes.
4. Press the crust half evenly into two 9-inch tart or pie pans, splitting it equally, pushing it up the sides. Chill the pans while you make the filling.
5. Preheat the oven to 400°F (200°C) with a rack in the lower third and a rimmed baking sheet on it.
6. Make the filling: in a large bowl, whisk the granulated sugar, cornstarch and nutmeg together, then gently fold in the peach, the raspberries, the lemon juice and the vanilla. Let stand 10 minutes.
7. Divide the filling evenly between the two chilled crusts.
8. Roll each lid disc on a floured surface to an 11-inch round, lay one over each tart, press the edges onto the crust rims to seal and cut four steam vents in each lid.
9. Brush the lids with the milk.
10. Set the tarts on the hot baking sheet and bake 20 minutes, then lower the oven to 375°F (190°C) and bake 35 to 40 minutes more, until the lids are deep golden and the filling bubbles thickly through the vents. Cover the edges with foil if they brown too fast.
11. Cool the tarts on a rack for at least 2 hours so the filling sets, then cut each into 6 slices.