Crust
1 1/2 cups graham cracker crumbs
3 tablespoons sugar
5 tablespoons melted butter

Filling
3 large egg yolks
14-ounce can sweetened condensed milk
1/3 cup Key lime juice or (approximately 9 to 10 Key limes, if you can find them)
2 teaspoons finely grated lime zest

Topping
2 1/2 to 3 cups fresh blueberries
1/2 cup water or fruit juice
pinch of salt
1 teaspoon lime juice
3 tablespoons sugar
1 tablespoon fruit and pastry glaze mix or cornstarch

Preheat the oven to 350°F.

To make the crust: Mix the ingredients and press them into a 9" removable bottom tart pan or 9" pie plate. Bake for 10 to 12 minutes, until lightly browned. Place on a rack to cool. Reduce the oven heat to 325°F.

To make the filling: Whisk together the egg yolks, condensed milk, and lime juice and zest until well blended; the mixture will thicken almost immediately. Pour into the crust and bake for 18 to 20 minutes, till just set. Remove from the oven, and cool at room temperature for several hours before topping.

To make the topping: Rinse the berries, and set aside all but 3/4 cup to dry. Stir together the water or fruit juice, salt, lime juice, sugar, and pastry glaze mix or cornstarch in a medium-sized saucepan set over medium heat, cooking till the sugar has dissolved. Add the 3/4 cup berries, and bring to a boil. Remove from the heat, pour over the reserved berries, and spoon onto the cooled tart. Chill for several hours. Serve with whipped cream, if desired. Yield: one 9" tart.