Make the puree: Place all ingredients in a food processor or blender and process until pureed. You should end up with about 1 2/3 cups strawberry puree. Divide the puree evenly between four 12.5 ounce jars (or six 8-oz jars). Add half of the chopped lady fingers to the jar and press them down into the puree using a spoon.
Make the cream: In the bowl of an electric mixer fitted with the whip attachment, beat heavy cream and sugar together on high speed until soft peaks form. Add mascarpone cheese a little at a time while beating on medium-high speed. Add the rum. Beat on high speed for 2 minutes longer or until the mixture is thick and fluffy. Pipe or spoon the cream on top of the biscuits and puree in the jars. Add the remaining biscuits on top of the cream in the jars. Top each jar with fresh blueberries and garnish with fresh mint.
Refrigerate for 1-2 hours to allow the biscuits to soften to cake-like consistency. Serve chilled.
Keyword July Fourth desserts, lady fingers, mascarpone cream, Tiramisu