-
Preheat oven to 375˚F.
-
In a medium-size bowl, combine powdered sugar, egg yolk and butter. Whisk until well combined. Add vanilla and flour and stir until all flour is incorporated.
-
Press into the sides and bottom of a 9 or 10-inch tart pan. I like to start on the sides and form a nice even layer, then work the rest of the dough into the bottom of the pan. Prick lightly with a fork and freeze for at least one hour.
-
Remove from freezer and press a sheet of foil tightly into the bottom and against the sides of the crust. Bake for 15 minutes, then remove foil and prick the bottom of the crust lightly with a fork again. Return to oven and bake another 13-15 minutes or until light golden brown. Remove from oven and allow to cool.
-
Place lemon juice in a small microwave-safe bowl. Sprinkle gelatin on top and stir. Allow to sit for 5 minutes. Mixture will be thick and gelatinous. Place in microwave and cook on high power for 15 seconds. Set aside.
-
In the bowl of an electric mixer, combine cream cheese and lemon zest. Beat for 2 minutes until very fluffy. Slowly add condensed milk, stopping several times to scrape the sides of the bowl. Continue beating for another minute.
-
Slowly add gelatin mixture while continuing to beat. Beat for 2 more minutes, stopping once to scrape the sides of the bowl. Pour into cooled shortbread crust and spread to an even layer. Refrigerate for at least 2 hours.
-
Place marmalade in a small microwave-safe bowl. Heat on high power for 1 minute. Pour through a fine mesh strive, pushing on solids with the back of a spoon. Discard solids.
-
Combine strained marmalade, blueberries and blackberries in a medium size bowl and stir to combine. Spoon fruit mixture over lemon layer. Refrigerate for 2 hours. Remove from refrigerator 20-30 minutes before serving. Garnish with fresh mint leaves, if desired.