Our daughter requests this tart for her birthday every year. It is a bit of work but the finished product is so worth the effort.
12 Tbsp Unsalted butter room temperature
1/2 c Sugar
1/2 tsp Vanilla extract
1 3/4 cup all purpose flour
pinch of salt
Lavender Earl Grey Buttercream
16 oz whole milk
3 Tbsp Zerama Tea Lavender Earl Grey
1 tsp Vanilla Extract
1 1/2 cup sugar
1/3 cup corn starch
2 egg yolks
16 oz unsalted butter room temperature
16 oz mascarpone cheese room temperatture
1/2 tsp salt
juice of one lemon
1 jar lemon curd
For Tart Crust:
Mix the butter and sugar together in the bowl of an electric mixer fitted with a paddle attachment until they are just combined. Add the vanilla. In a medium bowl, sift together the flour and salt, then add them to the butter-and-sugar mixture. Mix on low speed until the dough starts to come together. Dump onto a surface dusted with flour and shape into a flat disk. Press the dough into a 10-inch-round or 9-inch-square false-bottom tart pan, making sure that the finished edge is flat. Chill until firm.
Preheat the oven to 350 degrees F.
Butter 1 side of a square of aluminum foil to fit inside the chilled tart and place it, buttered side down, on the pastry. Fill with beans or rice. Bake for 20 minutes. Slowly lift the edge of the foil, if it sticks it needs to dry out more. Put back in oven and check every 2 minutes until the foil lifts off cleanly. Remove the foil and beans. Prick the tart all over with the tines of a fork, and bake again for 20 to 25 minutes more, or until lightly browned. If the edge is browning too quickly, cover it with a ring of foil or pie shield. Allow to cool to room temperature.
For Lavender Earl Grey Buttercream:
Bring milk to a simmer in a sauce pan, add the loose tea, cover, and let steep 5 minutes. Try not to let it go too long or the tea may become bitter. Give it a good stir and strain out the tea, squeezing the tea leaves to get out as much flavor as possible. I pour it through a coffee filter in a fine mesh strainer.
Whisk the cornstarch, sugar, yolks, and eggs in a mixing bowl. Bring the milk to a simmer. Once the milk comes to a simmer, whisk a ladle of the hot milk into the eggs. I do about two ladles to temper the eggs and then pour the warm egg mixture into the hot milk, whisking constantly. Cook this mixture at a simmer until thick and bubbly sluggishly. Cook for a full minute to ensure the cornstarch is cooked out.
Remove from heat and transfer to a large mixing bowl. At this point you're either going to need to cool it in the fridge or cool it in a stand mixer. The latter is faster and is what I usually do. To chill in the fridge cover the surface of the pastry cream with plastic wrap and refrigerate until completely cooled. To cool in a mixer, mix constantly on medium until the bowl is room temp to the touch. It should not be at all warm. If it is, your butter and cheese will melt when you add them. And it will not be awesome. If you have put it in the fridge, mix for a few minutes on medium until creamy before proceeding.
Once your pastry cream is cool, add the very soft butter one tablespoon at a time and then do the same with the mascarpone. Add the lemon and salt and whip to thoroughly combine. It should be smooth and creamy. At this point the frosting can be used, refrigerated, or frozen. Bring to room temp and whip until fluffy before using.
To Assemble Tart:
Fill your tart shell with the lemon curd, using an offset spatula.
Place in the refrigerator until completely chilled. Up to one day.
Once filled tart is chilled, fit a pastry bag (or ziplock) with a 1M tip and fill with buttercream. Cover the top of the tart with wide rosettes or the design of your choice, filling in any gaps. You will have leftover frosting that can be refrigerated or frozen for another use. Place frosted tart in refrigerator and chill completely. When ready to serve take the tart out of the fridge for 10 or 15 minutes.