Raspberry Vinegar Tart

Preparation

1. Step 1

   Prepare the crust: In a food processor, grind the cookies until you have 1½ cups crumbs. Transfer to a bowl. If using the freeze-dried raspberries, process them in a food processor, spice grinder or mortar and pestle until they are reduced to powder. There will be seeds, so sift the powder through a fine-mesh sieve into the cookie crumbs, and stir lightly to combine. Butter a 9-inch tart pan, put the crumbs in the middle and slowly drizzle the melted butter into the crumbs. Mix until the crumbs resemble the texture of wet sand. (You may not need all the butter; you can discard the rest.) Firmly press the crumbs against the sides and bottom of the pan until about ¼ inch thick.

2. Step 2

   Chill in the refrigerator, or even the freezer, for 1 hour. Preheat the oven to 350 degrees. Bake the crust until the base is dry, about 15 to 20 minutes. Remove from the oven and let cool completely. Keep the oven on.

3. Step 3

   Make the filling: Whisk together the eggs and ¼ cup sugar. In a 1-quart saucepan, whisk together the flour and remaining ¾ cup sugar, then whisk in water, red-wine vinegar and raspberry vinegar. Bring to a boil, whisking until the sugar is dissolved, then add to the egg mixture in a slow, steady stream, whisking vigorously to prevent the eggs from scrambling. Pour the filling back into the saucepan and cook over medium heat, stirring constantly with a wooden spoon, until it coats back of spoon, 12 to 15 minutes. Do not boil. Pour a ½-inch-thick layer of filling into the chilled tart crust.

4. Step 4

   Bake the pie in the middle of the oven until the filling is set, about 15 minutes, then cool completely in the pan. Chill in the refrigerator.

5. Step 5

   Whisk the heavy cream with the raspberry vinegar and St-Germain until stiff peaks form. Spread over the surface of the tart, then drizzle with a bit more raspberry vinegar.