These individual Meyer lemon tartlets contain four layers of lemon flavor, from the lemon thyme crust to the lemon meringue kiss. The crust and lemon curd can be made a day ahead.
For the tart crust, place flour, sugar, Thyme and lemon peel in food processor, cover and pulse to combine. Add butter, process until mixture resembles coarse crumbs. Add egg yolk and process until dough begins to form a ball. If needed add 1 to 2 tbs cold Limoncello liqueur. Divide dough in half and wrap each half in plastic wrap, pressing to form a disk. Refrigerate for at least 1 hour.
Cut each disk into 12 equal pieces, roll each piece on a lightly floured surface to 1/8 inch in thickness. Press into tartlet pans with 5cm (2-inch) diameter cups. Trim excess dough from top to form a total of 24 tart shells then freeze for 30 minutes.
Pre-heat oven to 180°C, 350°F, Gas Mark 4. Place tartlet pans on large baking tray and bake in the oven for 17-20 minutes or until lightly browned. Cool tart shells in their tray on a wire rack, then, using a toothpick, carefully remove tart shells from pans.
For the Meyer lemon curd, mix egg yolks, Meyer lemon juice, Limoncello liqueur and sugar in large heavy saucepan with wire whisk until well blended. Whisking constantly, cook on medium heat for 8-10 minutes or until curd is thickened and coats the back of a spoon. Remove from heat, then whisk in the butter, one piece at a time. Transfer to a large bowl, cover with plastic wrap pressing directly onto the surface of the curd to prevent a skin from forming. Refrigerate for at least 1 hour until chilled and curd is firm.
Meanwhile, for the Blackberries, mix all the ingredients in medium bowl until well blended then refrigerate until ready to serve. Spoon about 2 tbs lemon curd into each tart shell and set aside.
For the lemon meringue kisses, beat the egg whites in medium bowl with an electric mixer on high speed until foamy. Mix sugar and cream of tartar in small bowl and gradually add sugar mixture and Limoncello to the egg whites, beating until stiff peaks form. Spoon about 1 tbs of meringue in the center of each tartlet, lifting the spoon so that meringue forms a peak. Place tartlets onto large baking sheets.
Grill meringue kisses for 30 seconds to 1 minute or until the meringue is lightly browned. Refrigerate tartlets at least 30 minutes before serving. To serve, top each tartlet with the Limoncello Blackberries.
Cooks Notes: If Meyer lemons are unavailable, use grated lemon peel in the tart crust and the blackberry mixture. Use 100ml lemon juice and 50ml orange juice in the lemon curd.