Step 1Grease an 8-inch fluted tart pan with a removable bottom. Set it aside.
Step 2Grind the gingersnaps in a food processor to crumbs. Combine the crumbs, ginger, butter and brown sugar in the processor until well combined. Transfer the mixture to the tart pan, pressing it into the bottom and up sides to form an even crust (work through plastic wrap to make this easier). Place the shell in the freezer.
Step 3Meanwhile, place the cream cheese and sugar in the bowl of an electric mixer; beat them until fluffy. Add the lemon zest, lemon juice and lemon extract; beat until combined.
Step 4Whip the cream to stiff peaks, then fold it into the cream cheese mixture. Spoon the mixture into the prepared crust; use a spatula to make a decorative surface. Return the tart to the freezer until firm, at least 1 1/2 hours. (This can be frozen up to 1 month, wrapped airtight.)
Step 5To serve, let the tart rest at room temperature 30 minutes. Carefully remove the rim of the pan. Place the tart on a serving platter and surround it with the raspberries.