In a medium saucepan, combine 1 cup of blueberries with ½ cup of water over medium heat. Bring to a simmer, mashing blueberries. Strain to extract juice, return to pot, and add ½ cup sugar and 2 tablespoons lemon juice. Chill the syrup.

In a large bowl, whip 1 cup of heavy cream until stiff peaks form (3-4 minutes). In another bowl, beat 8 ounces of mascarpone cheese, ½ cup sugar, 1 teaspoon vanilla, and optional ½ teaspoon of almond extract until smooth. Fold in chilled blueberry syrup and then mix in whipped cream gently.

Dip ladyfingers into blueberry syrup briefly and arrange in layers. Spread half of the mascarpone filling over them. Repeat with remaining ladyfingers and filling, smoothing the top.

Cover with plastic wrap and refrigerate for at least 6 hours, preferably overnight.