For the Sweet Pastry Shell
1 1/4 cups (150 g) all-purpose flour
1/2 cup (60 g) powdered sugar
1/4 tsp fine sea salt
1/2 cup (113 g) unsalted butter, cold, cut into small cubes
1 large egg yolk
1–2 tbsp ice-cold water, as needed
For the Almond Cream (Frangipane)
6 tbsp (85 g) unsalted butter, softened
1/2 cup (100 g) granulated sugar
1 cup (100 g) finely ground blanched almond flour
1 large egg
1 tsp pure vanilla extract
1/4 tsp almond extract (optional but lovely)
1 tbsp (8 g) all-purpose flour
Pinch (about 1/8 tsp) fine sea salt
1 tbsp dark rum, brandy, or milk (optional, for extra flavor and softness)
For the Plum Topping
1 3/4 lb (800 g) ripe but firm plums (about 8–10 medium), halved, pitted, and thinly sliced
2 tbsp (25 g) granulated sugar, for sprinkling
1 tbsp apricot jam + 1 tsp water, warmed together (optional glaze)
1–2 tbsp sliced almonds (optional, for garnish)
Instructions
Step 1: Make the pastry dough
In a medium bowl, whisk together the flour, powdered sugar, and salt. Add the cold, cubed butter. Using your fingertips or a pastry cutter, rub or cut the butter into the dry ingredients until the mixture looks like coarse crumbs with some pea-sized bits of butter remaining. In a small bowl, lightly beat the egg yolk with 1 tbsp ice-cold water. Drizzle it over the flour mixture and toss with a fork until it starts to clump. If the dough seems too dry and sandy, add up to 1 extra tablespoon of cold water, a teaspoon at a time, just until it holds together when squeezed.
Turn the mixture onto a clean surface and gently press it into a cohesive disk. Avoid kneading; you want to keep the dough tender. Wrap tightly in plastic wrap and chill in the refrigerator for at least 1 hour (or up to 2 days). Chilling relaxes the gluten and firms the butter, which helps create a crisp, sturdy shell.
Step 2: Roll out, line the pan, and blind-bake the shell
Lightly flour your work surface and rolling pin. Roll the chilled dough into a circle about 11 inches (28 cm) in diameter and roughly 1/8 inch (3 mm) thick. If the dough cracks, simply patch it with scraps. Carefully transfer the dough to a 9-inch (23 cm) tart pan with a removable bottom, easing it into the corners without stretching. Press gently into the sides, then trim excess dough flush with the rim. Use leftover scraps to reinforce any thin spots.
Prick the base lightly with a fork. Place the pan in the freezer for 15–20 minutes while you preheat the oven to 375°F (190°C). Line the chilled shell with parchment paper or foil and fill with pie weights, dried beans, or rice. Blind-bake for 15 minutes. Carefully remove the weights and parchment, then return the shell to the oven for another 5–8 minutes, until the base looks dry and just lightly golden. Set aside to cool slightly while you make the almond cream.
Step 3: Prepare the almond cream
In a medium bowl, beat the softened butter and granulated sugar together with a hand mixer (or a sturdy whisk) until pale and creamy, 2–3 minutes. Add the egg and beat until fully incorporated and slightly thickened. Mix in the vanilla extract and almond extract (if using).
Sprinkle the almond flour, all-purpose flour, and salt over the mixture. Add the rum, brandy, or milk if using. Beat or stir just until smooth and well combined. The almond cream should be thick but easily spreadable. Avoid over-mixing at this stage; you do not want to whip in too much air, as that can cause the filling to puff dramatically and then sink.
Step 4: Prepare the plums
Rinse and dry the plums. Cut each plum in half, remove the pit, and place cut-side down on the cutting board. Slice each half into thin wedges, about 1/4 inch (6 mm) thick. Keeping the slices together in their original half-moon shapes makes it easier to fan them neatly over the tart later.
Choose plums that are ripe and sweet but still firm enough to hold their shape. Overly soft fruit can release too much juice and make the tart soggy; very underripe plums will be too tart and may not become jammy in the oven.
Step 5: Assemble the tart
Spread the almond cream evenly over the bottom of the still-slightly-warm tart shell, smoothing it with an offset spatula or the back of a spoon. Leave a small gap (about 1/4 inch / 6 mm) below the rim so the filling has room to puff slightly as it bakes.
Arrange the plum slices on top of the almond cream in tight, overlapping circles, starting from the outer edge and working toward the center. Fan each plum half slightly as you place it, so the slices spread like a deck of cards. Pack the fruit closely; it will shrink as it bakes. Sprinkle the 2 tablespoons granulated sugar evenly over the plums to encourage caramelization and a glossy, jammy finish.
Step 6: Bake until jammy and golden
Reduce the oven temperature, if needed, to 375°F (190°C). Place the assembled tart on a baking sheet (to catch any drips) and bake for 35–40 minutes. The almond cream should be puffed and golden at the edges, and the plums should look soft, bubbling, and deeply colored with slightly caramelized tips.
If the crust edge is browning too quickly before the filling is done, loosely cover the rim with strips of foil. The tart is ready when a toothpick inserted into the almond cream (between pieces of fruit) comes out mostly clean and the center no longer looks wet.
Step 7: Cool, glaze, and serve
Transfer the tart to a wire rack and let it cool completely in the pan, at least 45–60 minutes. This helps the almond cream set and the juices thicken, making slicing much easier.
If you would like a shiny finish, gently warm the apricot jam with 1 teaspoon of water until fluid, then brush it lightly over the plums with a pastry brush. Scatter a few sliced almonds around the outer edge if you like a bit of crunch and decoration. Remove the outer ring of the tart pan, slice into wedges with a sharp knife, and serve slightly warm or at room temperature. The tart is lovely on its own or with a spoonful of softly whipped cream or a dollop of crème fraîche.
Borrowed from:https://rhythmofthehome.com/caramelized-plum-tart-with-almond-cream-filling/