Sift the flour into a medium sized bowl. Add the brown sugar and salt and whisk together. Zest the lemon into the dry ingredients and rub it in with your fingers. Whisk in the egg and vanilla extract. Slowly add the heavy cream whisking continuously as you add the cream. Set the cream filling aside.
1/2 teaspoon kosher salt, 1 tablespoon (10 grams) unbleached all-purpose flour, 1/8 teaspoon kosher salt, 1/2 teaspoon lemon zest, 1 (50 grams) large egg, 1 teaspoon vanilla extract, 1/2 cup heavy cream
Cut the apricots in half. Sprinkle the almond flour over the bottom of the tart crust. Slowly pour the cream filling over the bottom of the crust. Starting on the inside edge of the pan, neatly overlap the halved apricots, cut side up, at an angle. Arrange in two or three concentric circles, working toward the center. Fill in the center with the remaining apricots.
1 tablespoon (7 grams) almond flour, 2 pounds fresh apricots (about 12 apricots)
Place the tart on a wire rack set in a rimmed baking sheet and bake the tart until the feeling registers between 170 - 175F in the center, about 60-70 minutes.
Remove the tart from the oven. Immediately stir together the apricot jam and water in a small saucepan and place it over medium heat. Cook it until the jam becomes warm and runny. Press the jam through a strainer to remove any large pieces of apricot. Brush the warm apricot glaze over the apricots (front and back) while it’s still warm.
1/4 cup apricot jam, 3 tablespoons water
Let the tart cool to room temperature before serving. If serving it the next day, refrigerate it until ready to serve.