This tart is made with easy-to-use puff pastry crust, a custardy filling, and fresh plums. It looks like a French country tart.
1 sheet frozen puff pastry (from a 17.3 oz box)
6 plums, a little soft, just not too ripe
4 tablespoons butter, plus extra for greasing
1 large egg plus 1 yolk
1/3 cup plus 1 tablespoon sugar, divided
1/2 teaspoon pure vanilla extract
1/3 cup all-purpose flour
1/4 teaspoon baking powder
1 tablespoon whipping cream
Preheat the oven to 400°F. Move an oven rack to the lowest shelf.
Place a 9 or 10-inch tart ring or tart pan with a removable bottom on top of a parchment-lined cookie sheet. Take some soft margarine and with your finger, rub the margarine around the inside of the ring or sides of the tart pan or ring.
Take the sheet of puff pastry out of the freezer. Thaw the puff pastry at room temperature for 30 to 45 minutes or use the “Quick thaw method for puff pastry” (see Foolproof Tips and Techniques).
Unroll the pastry on top of a piece of parchment sprinkled with a little flour. Roll the pastry about 1 inch larger than your tart ring or pan. You will need to sprinkle some flour on your rolling pin so the pastry does not stick to it. Place your hand under the parchment and flip the pastry into the tart ring or pan, using your fingers to gently press the pastry into the corners. Peel the parchment off the pastry. Again, use your fingers to make sure the pastry is in the corners and then drape any extra dough over the top of the ring or pan. Roll your rolling pin along the top of the ring or pan to cut off the excess dough. Place in the freezer for 10 minutes while you prepare the plums and filling.
Take each plum, cut in half around the pit and then slice each half into 1/4-inch slices.
In a microwave-safe bowl, heat the butter in the microwave for 30 seconds to soften, but not completely melt it. In a bowl, place the whole egg and yolk, 1/3 cup of sugar, and vanilla and whisk. Add the flour and baking powder and mix with a wooden spoon or silicone spatula. Add the softened butter and whipping cream and mix well. Remove the pan from the freezer and spread this mixture evenly inside the tart ring or pan.
Take the plum slices and, starting on the outside of the pastry, place the slices on their sides, in concentric circles. Pack the plums in tightly. Bake on the bottom oven rack for 25 minutes. Sprinkle the remaining tablespoon of sugar on top. Place back in the oven on the middle rack and bake another 10 minutes. Remove to rack to cool. To serve, if you used a tart ring without a bottom, slide the tart onto a serving plate and then pull off the ring. For a tart pan with a removable bottom, place your hand under the bottom and lift the tart up and out of the ring. Store covered with plastic at room temperature for five days or freeze for up to three months.